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Groups > linux.kernel > #1547586 > unrolled thread
| Started by | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| First post | 2016-12-27 14:00 +0100 |
| Last post | 2017-01-07 13:50 +0100 |
| Articles | 20 on this page of 62 — 10 participants |
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[PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-27 14:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2016-12-27 15:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-27 15:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-12-27 23:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Valdis.Kletnieks@vt.edu - 2016-12-27 23:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-12-28 09:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-28 10:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2016-12-28 15:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Valdis.Kletnieks@vt.edu - 2016-12-29 05:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-28 09:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2016-12-28 15:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Jean Delvare <jdelvare@suse.de> - 2017-01-04 10:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Michał Kępień <kernel@kempniu.pl> - 2016-12-29 09:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-29 10:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Michał Kępień <kernel@kempniu.pl> - 2016-12-29 14:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-29 15:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Michał Kępień <kernel@kempniu.pl> - 2016-12-29 22:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2016-12-29 22:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-03 10:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-03 10:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-03 19:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-03 20:00 +0100
RE: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines <Mario.Limonciello@dell.com> - 2017-01-03 20:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-03 20:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-03 21:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-03 21:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-03 21:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-03 22:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 09:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 10:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 10:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 11:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 11:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 11:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 12:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 13:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 14:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 17:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 18:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2017-01-04 18:50 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-04 19:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 23:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-04 23:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-04 23:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2017-01-04 23:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-04 23:10 +0100
Re: [PATCH] i2c: do not enable fall back to Host Notify by default kbuild test robot <lkp@intel.com> - 2017-01-05 03:30 +0100
Re: [PATCH] i2c: do not enable fall back to Host Notify by default kbuild test robot <lkp@intel.com> - 2017-01-05 03:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-05 10:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-05 10:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Jean Delvare <jdelvare@suse.de> - 2017-01-04 20:10 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-01-04 11:00 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 11:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 12:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 13:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-03 22:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2017-01-04 07:40 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Pali Rohár <pali.rohar@gmail.com> - 2017-01-04 10:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2017-01-04 10:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-01-03 21:30 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Jean Delvare <jdelvare@suse.de> - 2017-01-04 11:20 +0100
Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines Wolfram Sang <wsa@the-dreams.de> - 2017-01-07 13:50 +0100
Page 2 of 4 — ← Prev page 1 [2] 3 4 Next page →
| From | Dmitry Torokhov <dmitry.torokhov@gmail.com> |
|---|---|
| Date | 2017-01-03 19:40 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVCa6-1SP-19@gated-at.bofh.it> |
| In reply to | #1549628 |
On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires wrote:
> On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień wrote:
> > > > > > > > Dell platform team told us that some (DMI whitelisted) Dell
> > > > > > > > Latitude machines have ST microelectronics accelerometer at
> > > > > > > > i2c address 0x29. That i2c address is not specified in DMI
> > > > > > > > or ACPI, so runtime detection without whitelist which is
> > > > > > > > below is not possible.
> > > > > > > >
> > > > > > > > Presence of that ST microelectronics accelerometer is
> > > > > > > > verified by existence of SMO88xx ACPI device which
> > > > > > > > represent that accelerometer. Unfortunately without i2c
> > > > > > > > address.
> > > > > > >
> > > > > > > This part of the commit message sounded a bit confusing to me
> > > > > > > at first because there is already an ACPI driver which
> > > > > > > handles SMO88xx
> > > > > > >
> > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > * the purpose of this patch is to expose a richer interface
> > > > > > > (as
> > > > > > >
> > > > > > > provided by lis3lv02d) to these devices on some machines,
> > > > > > >
> > > > > > > * on whitelisted machines, dell-smo8800 and lis3lv02d can
> > > > > > > work
> > > > > > >
> > > > > > > simultaneously (even though dell-smo8800 effectively
> > > > > > > duplicates the work that lis3lv02d does).
> > > > > >
> > > > > > No. dell-smo8800 reads from ACPI irq number and exports
> > > > > > /dev/freefall device which notify userspace about falls.
> > > > > > lis3lv02d is i2c driver which exports axes of accelerometer.
> > > > > > Additionaly lis3lv02d can export also /dev/freefall if
> > > > > > registerer of i2c device provides irq number -- which is not
> > > > > > case of this patch.
> > > > > >
> > > > > > So both drivers are doing different things and both are useful.
> > > > > >
> > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > >
> > > > > > Yes, in ideal world irq number should be passed to lis3lv02d
> > > > > > driver and that would export whole device (with /dev/freefall
> > > > > > too), but due to HW abstraction it is too much complicated...
> > > > >
> > > > > Why? AFAICT, all that is required to pass that IRQ number all
> > > > > the way down to lis3lv02d is to set the irq field of the struct
> > > > > i2c_board_info you are passing to i2c_new_device(). And you can
> > > > > extract that IRQ number e.g. in check_acpi_smo88xx_device().
> > > > > However, you would then need to make sure dell-smo8800 does not
> > > > > attempt to request the same IRQ on whitelisted machines. This
> > > > > got me thinking about a way to somehow incorporate your changes
> > > > > into dell-smo8800 using Wolfram's bus_notifier suggestion, but I
> > > > > do not have a working solution for now. What is tempting about
> > > > > this approach is that you would not have to scan the ACPI
> > > > > namespace in search of SMO88xx devices, because smo8800_add() is
> > > > > automatically called for them. However, I fear that the
> > > > > resulting solution may be more complicated than the one you
> > > > > submitted.
> > > >
> > > > Then we need to deal with lot of problems. Order of loading .ko
> > > > modules is undefined. Binding devices to drivers registered by .ko
> > > > module is also in "random" order. At any time any of those .ko
> > > > module can be unloaded or at least device unbind (via sysfs) from
> > > > driver... And there can be some pathological situation (thanks to
> > > > adding ACPI layer as Andy pointed) that there will be more SMO88xx
> > > > devices in ACPI. Plus you can compile kernel with and without
> > > > those modules and also you can blacklist loading them (so compile
> > > > time check is not enough). And still some correct message notifier
> > > > must be used.
> > > >
> > > > I think such solution is much much more complicated, there are lot
> > > > of combinations of kernel configuration and available dell
> > > > devices...
> > >
> > > I tried a few more things, but ultimately failed to find a nice way
> > > to implement this.
> > >
> > > Another issue popped up, though. Linus' master branch contains a
> > > recent commit by Benjamin Tissoires (CC'ed), 4d5538f5882a ("i2c: use
> > > an IRQ to report Host Notify events, not alert") which breaks your
> > > patch. The reason for that is that lis3lv02d relies on the i2c
> > > client's IRQ being 0 to detect that it should not create
> > > /dev/freefall. Benjamin's patch causes the Host Notify IRQ to be
> > > assigned to the i2c client your patch creates, thus causing
> > > lis3lv02d to create /dev/freefall, which in turn conflicts with
> > > dell-smo8800 which is trying to create /dev/freefall itself.
> >
> > So 4d5538f5882a is breaking lis3lv02d driver...
>
> Apologies for that.
>
> I could easily fix this by adding a kernel API to know whether the
> provided irq is from Host Notify or if it was coming from an actual
> declaration. However, I have no idea how many other drivers would
> require this (hopefully only this one).
>
> One other solution would be to reserve the Host Notify IRQ and let the
> actual drivers that need it to set it, but this was not the best
> solution according to Dmitri. On my side, I am not entirely against this
> given that it's a chip feature, so the driver should be able to know
> that it's available.
>
> Dmitri, Wolfram, Jean, any preferences?
I read this:
"IIRC both dell-smo8800 and lis3lv02d represent one HW device (that ST
microelectronics accelerometer) but due to complicated HW abstraction
and layers on Dell laptops it is handled by two drivers, one ACPI and
one i2c."
and that is the core of the issue. You have 2 drivers fighting over the
same device. Fix this and it will all work.
As far as I can see hp_accel instantiates lis3lv02d and accesses it via
ACPI methods, can the same be done for Dell?
>
> >
> > > Also, just to make sure we do not overthink this, I understand that
> > > not every unit of the models from the whitelist has an
> > > accelerometer, correct? In other words, could we perhaps skip the
> > > part where we are making sure the SMO88xx ACPI device is there?
> >
> > Good question... At least for E6440 I'm did not thing it was possible to
> > configure notebook without "3 axes free fall sensor".
> >
> > But! In BIOS SETUP it is possible to disable free fall sensor. I will
> > try to disable it there and will check what happen. My guess is that it
> > will be disabled in ACPI.
>
> Just adding my 2 cents regarding the whitelist and interaction between
> those 2 drivers. I find this very fragile to have only one available
> /dev/freefall node and to rely on the fairness of each driver to not bind
> one. It would have been much simpler to have /dev/freefallXX and a
> proper misc class device for it. This way, we don't even need to
> mutually exclude the drivers. But this is already 8 years old code, so I
> guess userspace expects this... (why isn't that using the input subsystem
> at all?).
I do not consider throwing a unit down an ordinary user interaction ;)
So there is no input event code for this.
Userspace should really use IIO accelerometer interface here. And kernel
could provide composite IIO->/dev/freefall bridge, like we did for
/dev/input/mice when all userspace wanted only PS/2.
Thanks.
--
Dmitry
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| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-03 20:00 +0100 |
| Message-ID | <sVCts-1ZW-5@gated-at.bofh.it> |
| In reply to | #1550075 |
[Multipart message — attachments visible in raw view] — view raw
On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires wrote:
> > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień wrote:
> > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > microelectronics accelerometer at i2c address 0x29.
> > > > > > > > > That i2c address is not specified in DMI or ACPI, so
> > > > > > > > > runtime detection without whitelist which is below
> > > > > > > > > is not possible.
> > > > > > > > >
> > > > > > > > > Presence of that ST microelectronics accelerometer is
> > > > > > > > > verified by existence of SMO88xx ACPI device which
> > > > > > > > > represent that accelerometer. Unfortunately without
> > > > > > > > > i2c address.
> > > > > > > >
> > > > > > > > This part of the commit message sounded a bit confusing
> > > > > > > > to me at first because there is already an ACPI driver
> > > > > > > > which handles SMO88xx
> > > > > > > >
> > > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > > * the purpose of this patch is to expose a richer
> > > > > > > > interface (as
> > > > > > > >
> > > > > > > > provided by lis3lv02d) to these devices on some
> > > > > > > > machines,
> > > > > > > >
> > > > > > > > * on whitelisted machines, dell-smo8800 and lis3lv02d
> > > > > > > > can work
> > > > > > > >
> > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > effectively duplicates the work that lis3lv02d
> > > > > > > > does).
> > > > > > >
> > > > > > > No. dell-smo8800 reads from ACPI irq number and exports
> > > > > > > /dev/freefall device which notify userspace about falls.
> > > > > > > lis3lv02d is i2c driver which exports axes of
> > > > > > > accelerometer. Additionaly lis3lv02d can export also
> > > > > > > /dev/freefall if registerer of i2c device provides irq
> > > > > > > number -- which is not case of this patch.
> > > > > > >
> > > > > > > So both drivers are doing different things and both are
> > > > > > > useful.
> > > > > > >
> > > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW
> > > > > > > device (that ST microelectronics accelerometer) but due
> > > > > > > to complicated HW abstraction and layers on Dell laptops
> > > > > > > it is handled by two drivers, one ACPI and one i2c.
> > > > > > >
> > > > > > > Yes, in ideal world irq number should be passed to
> > > > > > > lis3lv02d driver and that would export whole device
> > > > > > > (with /dev/freefall too), but due to HW abstraction it
> > > > > > > is too much complicated...
> > > > > >
> > > > > > Why? AFAICT, all that is required to pass that IRQ number
> > > > > > all the way down to lis3lv02d is to set the irq field of
> > > > > > the struct i2c_board_info you are passing to
> > > > > > i2c_new_device(). And you can extract that IRQ number
> > > > > > e.g. in check_acpi_smo88xx_device(). However, you would
> > > > > > then need to make sure dell-smo8800 does not attempt to
> > > > > > request the same IRQ on whitelisted machines. This got me
> > > > > > thinking about a way to somehow incorporate your changes
> > > > > > into dell-smo8800 using Wolfram's bus_notifier suggestion,
> > > > > > but I do not have a working solution for now. What is
> > > > > > tempting about this approach is that you would not have to
> > > > > > scan the ACPI namespace in search of SMO88xx devices,
> > > > > > because smo8800_add() is automatically called for them.
> > > > > > However, I fear that the resulting solution may be more
> > > > > > complicated than the one you submitted.
> > > > >
> > > > > Then we need to deal with lot of problems. Order of loading
> > > > > .ko modules is undefined. Binding devices to drivers
> > > > > registered by .ko module is also in "random" order. At any
> > > > > time any of those .ko module can be unloaded or at least
> > > > > device unbind (via sysfs) from driver... And there can be
> > > > > some pathological situation (thanks to adding ACPI layer as
> > > > > Andy pointed) that there will be more SMO88xx devices in
> > > > > ACPI. Plus you can compile kernel with and without those
> > > > > modules and also you can blacklist loading them (so compile
> > > > > time check is not enough). And still some correct message
> > > > > notifier must be used.
> > > > >
> > > > > I think such solution is much much more complicated, there
> > > > > are lot of combinations of kernel configuration and
> > > > > available dell devices...
> > > >
> > > > I tried a few more things, but ultimately failed to find a nice
> > > > way to implement this.
> > > >
> > > > Another issue popped up, though. Linus' master branch contains
> > > > a recent commit by Benjamin Tissoires (CC'ed), 4d5538f5882a
> > > > ("i2c: use an IRQ to report Host Notify events, not alert")
> > > > which breaks your patch. The reason for that is that
> > > > lis3lv02d relies on the i2c client's IRQ being 0 to detect
> > > > that it should not create /dev/freefall. Benjamin's patch
> > > > causes the Host Notify IRQ to be assigned to the i2c client
> > > > your patch creates, thus causing lis3lv02d to create
> > > > /dev/freefall, which in turn conflicts with dell-smo8800 which
> > > > is trying to create /dev/freefall itself.
> > >
> > > So 4d5538f5882a is breaking lis3lv02d driver...
> >
> > Apologies for that.
> >
> > I could easily fix this by adding a kernel API to know whether the
> > provided irq is from Host Notify or if it was coming from an actual
> > declaration. However, I have no idea how many other drivers would
> > require this (hopefully only this one).
> >
> > One other solution would be to reserve the Host Notify IRQ and let
> > the actual drivers that need it to set it, but this was not the
> > best solution according to Dmitri. On my side, I am not entirely
> > against this given that it's a chip feature, so the driver should
> > be able to know that it's available.
> >
> > Dmitri, Wolfram, Jean, any preferences?
>
> I read this:
>
> "IIRC both dell-smo8800 and lis3lv02d represent one HW device (that
> ST microelectronics accelerometer) but due to complicated HW
> abstraction and layers on Dell laptops it is handled by two drivers,
> one ACPI and one i2c."
>
> and that is the core of the issue. You have 2 drivers fighting over
> the same device. Fix this and it will all work.
With my current implementation (which I sent in this patch), they are
not fighting.
dell-smo8800 exports /dev/freefall (and nothing more) and lis3lv02d only
accelerometer device as lis3lv02d driver does not get IRQ number in
platform data.
> As far as I can see hp_accel instantiates lis3lv02d and accesses it
> via ACPI methods, can the same be done for Dell?
No, Dell does not have any ACPI methods. And as I wrote in ACPI or DMI
is even not i2c address of device, so it needs to be specified in code
itself.
Really there is no other way... :-(
> > > > Also, just to make sure we do not overthink this, I understand
> > > > that not every unit of the models from the whitelist has an
> > > > accelerometer, correct? In other words, could we perhaps skip
> > > > the part where we are making sure the SMO88xx ACPI device is
> > > > there?
> > >
> > > Good question... At least for E6440 I'm did not thing it was
> > > possible to configure notebook without "3 axes free fall
> > > sensor".
> > >
> > > But! In BIOS SETUP it is possible to disable free fall sensor. I
> > > will try to disable it there and will check what happen. My
> > > guess is that it will be disabled in ACPI.
> >
> > Just adding my 2 cents regarding the whitelist and interaction
> > between those 2 drivers. I find this very fragile to have only one
> > available /dev/freefall node and to rely on the fairness of each
> > driver to not bind one. It would have been much simpler to have
> > /dev/freefallXX and a proper misc class device for it. This way,
> > we don't even need to mutually exclude the drivers. But this is
> > already 8 years old code, so I guess userspace expects this...
> > (why isn't that using the input subsystem at all?).
>
> I do not consider throwing a unit down an ordinary user interaction
> ;) So there is no input event code for this.
>
> Userspace should really use IIO accelerometer interface here. And
> kernel could provide composite IIO->/dev/freefall bridge, like we
Such "generic" bridge is probably not possible, as /dev/freefall is
connected to specific lis3lv02d IRQ.
> did for /dev/input/mice when all userspace wanted only PS/2.
>
> Thanks.
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | <Mario.Limonciello@dell.com> |
|---|---|
| Date | 2017-01-03 20:10 +0100 |
| Subject | RE: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVCD7-2iN-5@gated-at.bofh.it> |
| In reply to | #1550092 |
> -----Original Message-----
> From: Pali Rohár [mailto:pali.rohar@gmail.com]
> Sent: Tuesday, January 3, 2017 12:50 PM
> To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>; Michał Kępień
> <kernel@kempniu.pl>; Jean Delvare <jdelvare@suse.com>; Wolfram Sang
> <wsa@the-dreams.de>; Steven Honeyman <stevenhoneyman@gmail.com>;
> Valdis.Kletnieks@vt.edu; Jochen Eisinger <jochen@penguin-breeder.org>;
> Gabriele Mazzotta <gabriele.mzt@gmail.com>; Andy Lutomirski
> <luto@kernel.org>; Limonciello, Mario <Mario_Limonciello@Dell.com>; Alex
> Hung <alex.hung@canonical.com>; Takashi Iwai <tiwai@suse.de>; linux-
> i2c@vger.kernel.org; linux-kernel@vger.kernel.org; platform-driver-
> x86@vger.kernel.org
> Subject: Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell
> machines
>
> On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires wrote:
> > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień wrote:
> > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > microelectronics accelerometer at i2c address 0x29.
> > > > > > > > > > That i2c address is not specified in DMI or ACPI, so
> > > > > > > > > > runtime detection without whitelist which is below is
> > > > > > > > > > not possible.
> > > > > > > > > >
> > > > > > > > > > Presence of that ST microelectronics accelerometer is
> > > > > > > > > > verified by existence of SMO88xx ACPI device which
> > > > > > > > > > represent that accelerometer. Unfortunately without
> > > > > > > > > > i2c address.
> > > > > > > > >
> > > > > > > > > This part of the commit message sounded a bit confusing
> > > > > > > > > to me at first because there is already an ACPI driver
> > > > > > > > > which handles SMO88xx
> > > > > > > > >
> > > > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > > > * the purpose of this patch is to expose a richer
> > > > > > > > > interface (as
> > > > > > > > >
> > > > > > > > > provided by lis3lv02d) to these devices on some
> > > > > > > > > machines,
> > > > > > > > >
> > > > > > > > > * on whitelisted machines, dell-smo8800 and lis3lv02d
> > > > > > > > > can work
> > > > > > > > >
> > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > effectively duplicates the work that lis3lv02d
> > > > > > > > > does).
> > > > > > > >
> > > > > > > > No. dell-smo8800 reads from ACPI irq number and exports
> > > > > > > > /dev/freefall device which notify userspace about falls.
> > > > > > > > lis3lv02d is i2c driver which exports axes of
> > > > > > > > accelerometer. Additionaly lis3lv02d can export also
> > > > > > > > /dev/freefall if registerer of i2c device provides irq
> > > > > > > > number -- which is not case of this patch.
> > > > > > > >
> > > > > > > > So both drivers are doing different things and both are
> > > > > > > > useful.
> > > > > > > >
> > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW
> > > > > > > > device (that ST microelectronics accelerometer) but due to
> > > > > > > > complicated HW abstraction and layers on Dell laptops it
> > > > > > > > is handled by two drivers, one ACPI and one i2c.
> > > > > > > >
> > > > > > > > Yes, in ideal world irq number should be passed to
> > > > > > > > lis3lv02d driver and that would export whole device (with
> > > > > > > > /dev/freefall too), but due to HW abstraction it is too
> > > > > > > > much complicated...
> > > > > > >
> > > > > > > Why? AFAICT, all that is required to pass that IRQ number
> > > > > > > all the way down to lis3lv02d is to set the irq field of the
> > > > > > > struct i2c_board_info you are passing to i2c_new_device().
> > > > > > > And you can extract that IRQ number e.g. in
> > > > > > > check_acpi_smo88xx_device(). However, you would then need to
> > > > > > > make sure dell-smo8800 does not attempt to request the same
> > > > > > > IRQ on whitelisted machines. This got me thinking about a
> > > > > > > way to somehow incorporate your changes into dell-smo8800
> > > > > > > using Wolfram's bus_notifier suggestion, but I do not have a
> > > > > > > working solution for now. What is tempting about this
> > > > > > > approach is that you would not have to scan the ACPI
> > > > > > > namespace in search of SMO88xx devices, because
> > > > > > > smo8800_add() is automatically called for them.
> > > > > > > However, I fear that the resulting solution may be more
> > > > > > > complicated than the one you submitted.
> > > > > >
> > > > > > Then we need to deal with lot of problems. Order of loading
> > > > > > .ko modules is undefined. Binding devices to drivers
> > > > > > registered by .ko module is also in "random" order. At any
> > > > > > time any of those .ko module can be unloaded or at least
> > > > > > device unbind (via sysfs) from driver... And there can be some
> > > > > > pathological situation (thanks to adding ACPI layer as Andy
> > > > > > pointed) that there will be more SMO88xx devices in ACPI. Plus
> > > > > > you can compile kernel with and without those modules and also
> > > > > > you can blacklist loading them (so compile time check is not
> > > > > > enough). And still some correct message notifier must be used.
> > > > > >
> > > > > > I think such solution is much much more complicated, there are
> > > > > > lot of combinations of kernel configuration and available dell
> > > > > > devices...
> > > > >
> > > > > I tried a few more things, but ultimately failed to find a nice
> > > > > way to implement this.
> > > > >
> > > > > Another issue popped up, though. Linus' master branch contains
> > > > > a recent commit by Benjamin Tissoires (CC'ed), 4d5538f5882a
> > > > > ("i2c: use an IRQ to report Host Notify events, not alert")
> > > > > which breaks your patch. The reason for that is that lis3lv02d
> > > > > relies on the i2c client's IRQ being 0 to detect that it should
> > > > > not create /dev/freefall. Benjamin's patch causes the Host
> > > > > Notify IRQ to be assigned to the i2c client your patch creates,
> > > > > thus causing lis3lv02d to create /dev/freefall, which in turn
> > > > > conflicts with dell-smo8800 which is trying to create
> > > > > /dev/freefall itself.
> > > >
> > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > >
> > > Apologies for that.
> > >
> > > I could easily fix this by adding a kernel API to know whether the
> > > provided irq is from Host Notify or if it was coming from an actual
> > > declaration. However, I have no idea how many other drivers would
> > > require this (hopefully only this one).
> > >
> > > One other solution would be to reserve the Host Notify IRQ and let
> > > the actual drivers that need it to set it, but this was not the best
> > > solution according to Dmitri. On my side, I am not entirely against
> > > this given that it's a chip feature, so the driver should be able to
> > > know that it's available.
> > >
> > > Dmitri, Wolfram, Jean, any preferences?
> >
> > I read this:
> >
> > "IIRC both dell-smo8800 and lis3lv02d represent one HW device (that ST
> > microelectronics accelerometer) but due to complicated HW abstraction
> > and layers on Dell laptops it is handled by two drivers, one ACPI and
> > one i2c."
> >
> > and that is the core of the issue. You have 2 drivers fighting over
> > the same device. Fix this and it will all work.
>
> With my current implementation (which I sent in this patch), they are not
> fighting.
>
> dell-smo8800 exports /dev/freefall (and nothing more) and lis3lv02d only
> accelerometer device as lis3lv02d driver does not get IRQ number in platform
> data.
>
> > As far as I can see hp_accel instantiates lis3lv02d and accesses it
> > via ACPI methods, can the same be done for Dell?
>
> No, Dell does not have any ACPI methods. And as I wrote in ACPI or DMI is even
> not i2c address of device, so it needs to be specified in code itself.
>
> Really there is no other way... :-(
Dell doesn't export the general purpose accelerometer
data up to the OS.
Pali wanted it however and came up with a way to access it though
from the information we have shared.
That's the reason that there is no ACPI method for this and it needs
to be whitelisted in this driver on the platforms that have it wired
up this way.
>
> > > > > Also, just to make sure we do not overthink this, I understand
> > > > > that not every unit of the models from the whitelist has an
> > > > > accelerometer, correct? In other words, could we perhaps skip
> > > > > the part where we are making sure the SMO88xx ACPI device is
> > > > > there?
> > > >
> > > > Good question... At least for E6440 I'm did not thing it was
> > > > possible to configure notebook without "3 axes free fall sensor".
> > > >
> > > > But! In BIOS SETUP it is possible to disable free fall sensor. I
> > > > will try to disable it there and will check what happen. My guess
> > > > is that it will be disabled in ACPI.
> > >
> > > Just adding my 2 cents regarding the whitelist and interaction
> > > between those 2 drivers. I find this very fragile to have only one
> > > available /dev/freefall node and to rely on the fairness of each
> > > driver to not bind one. It would have been much simpler to have
> > > /dev/freefallXX and a proper misc class device for it. This way, we
> > > don't even need to mutually exclude the drivers. But this is already
> > > 8 years old code, so I guess userspace expects this...
> > > (why isn't that using the input subsystem at all?).
> >
> > I do not consider throwing a unit down an ordinary user interaction
> > ;) So there is no input event code for this.
> >
> > Userspace should really use IIO accelerometer interface here. And
> > kernel could provide composite IIO->/dev/freefall bridge, like we
>
> Such "generic" bridge is probably not possible, as /dev/freefall is connected to
> specific lis3lv02d IRQ.
>
> > did for /dev/input/mice when all userspace wanted only PS/2.
> >
> > Thanks.
>
> --
> Pali Rohár
> pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Dmitry Torokhov <dmitry.torokhov@gmail.com> |
|---|---|
| Date | 2017-01-03 20:50 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVDfP-2y2-17@gated-at.bofh.it> |
| In reply to | #1550092 |
On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires wrote:
> > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień wrote:
> > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > microelectronics accelerometer at i2c address 0x29.
> > > > > > > > > > That i2c address is not specified in DMI or ACPI, so
> > > > > > > > > > runtime detection without whitelist which is below
> > > > > > > > > > is not possible.
> > > > > > > > > >
> > > > > > > > > > Presence of that ST microelectronics accelerometer is
> > > > > > > > > > verified by existence of SMO88xx ACPI device which
> > > > > > > > > > represent that accelerometer. Unfortunately without
> > > > > > > > > > i2c address.
> > > > > > > > >
> > > > > > > > > This part of the commit message sounded a bit confusing
> > > > > > > > > to me at first because there is already an ACPI driver
> > > > > > > > > which handles SMO88xx
> > > > > > > > >
> > > > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > > > * the purpose of this patch is to expose a richer
> > > > > > > > > interface (as
> > > > > > > > >
> > > > > > > > > provided by lis3lv02d) to these devices on some
> > > > > > > > > machines,
> > > > > > > > >
> > > > > > > > > * on whitelisted machines, dell-smo8800 and lis3lv02d
> > > > > > > > > can work
> > > > > > > > >
> > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > effectively duplicates the work that lis3lv02d
> > > > > > > > > does).
> > > > > > > >
> > > > > > > > No. dell-smo8800 reads from ACPI irq number and exports
> > > > > > > > /dev/freefall device which notify userspace about falls.
> > > > > > > > lis3lv02d is i2c driver which exports axes of
> > > > > > > > accelerometer. Additionaly lis3lv02d can export also
> > > > > > > > /dev/freefall if registerer of i2c device provides irq
> > > > > > > > number -- which is not case of this patch.
> > > > > > > >
> > > > > > > > So both drivers are doing different things and both are
> > > > > > > > useful.
> > > > > > > >
> > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW
> > > > > > > > device (that ST microelectronics accelerometer) but due
> > > > > > > > to complicated HW abstraction and layers on Dell laptops
> > > > > > > > it is handled by two drivers, one ACPI and one i2c.
> > > > > > > >
> > > > > > > > Yes, in ideal world irq number should be passed to
> > > > > > > > lis3lv02d driver and that would export whole device
> > > > > > > > (with /dev/freefall too), but due to HW abstraction it
> > > > > > > > is too much complicated...
> > > > > > >
> > > > > > > Why? AFAICT, all that is required to pass that IRQ number
> > > > > > > all the way down to lis3lv02d is to set the irq field of
> > > > > > > the struct i2c_board_info you are passing to
> > > > > > > i2c_new_device(). And you can extract that IRQ number
> > > > > > > e.g. in check_acpi_smo88xx_device(). However, you would
> > > > > > > then need to make sure dell-smo8800 does not attempt to
> > > > > > > request the same IRQ on whitelisted machines. This got me
> > > > > > > thinking about a way to somehow incorporate your changes
> > > > > > > into dell-smo8800 using Wolfram's bus_notifier suggestion,
> > > > > > > but I do not have a working solution for now. What is
> > > > > > > tempting about this approach is that you would not have to
> > > > > > > scan the ACPI namespace in search of SMO88xx devices,
> > > > > > > because smo8800_add() is automatically called for them.
> > > > > > > However, I fear that the resulting solution may be more
> > > > > > > complicated than the one you submitted.
> > > > > >
> > > > > > Then we need to deal with lot of problems. Order of loading
> > > > > > .ko modules is undefined. Binding devices to drivers
> > > > > > registered by .ko module is also in "random" order. At any
> > > > > > time any of those .ko module can be unloaded or at least
> > > > > > device unbind (via sysfs) from driver... And there can be
> > > > > > some pathological situation (thanks to adding ACPI layer as
> > > > > > Andy pointed) that there will be more SMO88xx devices in
> > > > > > ACPI. Plus you can compile kernel with and without those
> > > > > > modules and also you can blacklist loading them (so compile
> > > > > > time check is not enough). And still some correct message
> > > > > > notifier must be used.
> > > > > >
> > > > > > I think such solution is much much more complicated, there
> > > > > > are lot of combinations of kernel configuration and
> > > > > > available dell devices...
> > > > >
> > > > > I tried a few more things, but ultimately failed to find a nice
> > > > > way to implement this.
> > > > >
> > > > > Another issue popped up, though. Linus' master branch contains
> > > > > a recent commit by Benjamin Tissoires (CC'ed), 4d5538f5882a
> > > > > ("i2c: use an IRQ to report Host Notify events, not alert")
> > > > > which breaks your patch. The reason for that is that
> > > > > lis3lv02d relies on the i2c client's IRQ being 0 to detect
> > > > > that it should not create /dev/freefall. Benjamin's patch
> > > > > causes the Host Notify IRQ to be assigned to the i2c client
> > > > > your patch creates, thus causing lis3lv02d to create
> > > > > /dev/freefall, which in turn conflicts with dell-smo8800 which
> > > > > is trying to create /dev/freefall itself.
> > > >
> > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > >
> > > Apologies for that.
> > >
> > > I could easily fix this by adding a kernel API to know whether the
> > > provided irq is from Host Notify or if it was coming from an actual
> > > declaration. However, I have no idea how many other drivers would
> > > require this (hopefully only this one).
> > >
> > > One other solution would be to reserve the Host Notify IRQ and let
> > > the actual drivers that need it to set it, but this was not the
> > > best solution according to Dmitri. On my side, I am not entirely
> > > against this given that it's a chip feature, so the driver should
> > > be able to know that it's available.
> > >
> > > Dmitri, Wolfram, Jean, any preferences?
> >
> > I read this:
> >
> > "IIRC both dell-smo8800 and lis3lv02d represent one HW device (that
> > ST microelectronics accelerometer) but due to complicated HW
> > abstraction and layers on Dell laptops it is handled by two drivers,
> > one ACPI and one i2c."
> >
> > and that is the core of the issue. You have 2 drivers fighting over
> > the same device. Fix this and it will all work.
>
> With my current implementation (which I sent in this patch), they are
> not fighting.
>
> dell-smo8800 exports /dev/freefall (and nothing more) and lis3lv02d only
> accelerometer device as lis3lv02d driver does not get IRQ number in
> platform data.
>
> > As far as I can see hp_accel instantiates lis3lv02d and accesses it
> > via ACPI methods, can the same be done for Dell?
>
> No, Dell does not have any ACPI methods. And as I wrote in ACPI or DMI
> is even not i2c address of device, so it needs to be specified in code
> itself.
>
> Really there is no other way... :-(
Sure there is:
1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
2. dell-smo8800 provides read/write functions for lis3lv02d that simply
forward requests to dell-smo8800-accel i2c client.
3. dell-smo8800 instantiates lis3lv02d instance like hp_accel does.
Alternatively, can lis3lv02d be tasked to create /dev/freefall?
Yet another option: can we add a new flag to i2c_board_info controlling
whether we want to enable/disable wiring up host notify interrupt?
Benjamin, is there anything "special" in RMI SMbus ACPI descriptors we
could use?
Thanks.
--
Dmitry
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-03 21:10 +0100 |
| Message-ID | <sVDzc-2TT-5@gated-at.bofh.it> |
| In reply to | #1550130 |
[Multipart message — attachments visible in raw view] — view raw
On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > wrote:
> > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień
> > > > > > > > > wrote:
> > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > 0x29. That i2c address is not specified in DMI
> > > > > > > > > > > or ACPI, so runtime detection without whitelist
> > > > > > > > > > > which is below is not possible.
> > > > > > > > > > >
> > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > address.
> > > > > > > > > >
> > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > confusing to me at first because there is already
> > > > > > > > > > an ACPI driver which handles SMO88xx
> > > > > > > > > >
> > > > > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > > > > * the purpose of this patch is to expose a richer
> > > > > > > > > > interface (as
> > > > > > > > > >
> > > > > > > > > > provided by lis3lv02d) to these devices on some
> > > > > > > > > > machines,
> > > > > > > > > >
> > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > lis3lv02d can work
> > > > > > > > > >
> > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > effectively duplicates the work that lis3lv02d
> > > > > > > > > > does).
> > > > > > > > >
> > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > exports /dev/freefall device which notify userspace
> > > > > > > > > about falls. lis3lv02d is i2c driver which exports
> > > > > > > > > axes of accelerometer. Additionaly lis3lv02d can
> > > > > > > > > export also /dev/freefall if registerer of i2c
> > > > > > > > > device provides irq number -- which is not case of
> > > > > > > > > this patch.
> > > > > > > > >
> > > > > > > > > So both drivers are doing different things and both
> > > > > > > > > are useful.
> > > > > > > > >
> > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW
> > > > > > > > > device (that ST microelectronics accelerometer) but
> > > > > > > > > due to complicated HW abstraction and layers on Dell
> > > > > > > > > laptops it is handled by two drivers, one ACPI and
> > > > > > > > > one i2c.
> > > > > > > > >
> > > > > > > > > Yes, in ideal world irq number should be passed to
> > > > > > > > > lis3lv02d driver and that would export whole device
> > > > > > > > > (with /dev/freefall too), but due to HW abstraction
> > > > > > > > > it is too much complicated...
> > > > > > > >
> > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > number all the way down to lis3lv02d is to set the irq
> > > > > > > > field of the struct i2c_board_info you are passing to
> > > > > > > > i2c_new_device(). And you can extract that IRQ number
> > > > > > > > e.g. in check_acpi_smo88xx_device(). However, you would
> > > > > > > > then need to make sure dell-smo8800 does not attempt to
> > > > > > > > request the same IRQ on whitelisted machines. This got
> > > > > > > > me thinking about a way to somehow incorporate your
> > > > > > > > changes into dell-smo8800 using Wolfram's bus_notifier
> > > > > > > > suggestion, but I do not have a working solution for
> > > > > > > > now. What is tempting about this approach is that you
> > > > > > > > would not have to scan the ACPI namespace in search of
> > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > automatically called for them. However, I fear that
> > > > > > > > the resulting solution may be more complicated than
> > > > > > > > the one you submitted.
> > > > > > >
> > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > order. At any time any of those .ko module can be
> > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > driver... And there can be some pathological situation
> > > > > > > (thanks to adding ACPI layer as Andy pointed) that there
> > > > > > > will be more SMO88xx devices in ACPI. Plus you can
> > > > > > > compile kernel with and without those modules and also
> > > > > > > you can blacklist loading them (so compile time check is
> > > > > > > not enough). And still some correct message notifier
> > > > > > > must be used.
> > > > > > >
> > > > > > > I think such solution is much much more complicated,
> > > > > > > there are lot of combinations of kernel configuration
> > > > > > > and available dell devices...
> > > > > >
> > > > > > I tried a few more things, but ultimately failed to find a
> > > > > > nice way to implement this.
> > > > > >
> > > > > > Another issue popped up, though. Linus' master branch
> > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > events, not alert") which breaks your patch. The reason
> > > > > > for that is that lis3lv02d relies on the i2c client's IRQ
> > > > > > being 0 to detect that it should not create /dev/freefall.
> > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > assigned to the i2c client your patch creates, thus
> > > > > > causing lis3lv02d to create /dev/freefall, which in turn
> > > > > > conflicts with dell-smo8800 which is trying to create
> > > > > > /dev/freefall itself.
> > > > >
> > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > >
> > > > Apologies for that.
> > > >
> > > > I could easily fix this by adding a kernel API to know whether
> > > > the provided irq is from Host Notify or if it was coming from
> > > > an actual declaration. However, I have no idea how many other
> > > > drivers would require this (hopefully only this one).
> > > >
> > > > One other solution would be to reserve the Host Notify IRQ and
> > > > let the actual drivers that need it to set it, but this was
> > > > not the best solution according to Dmitri. On my side, I am
> > > > not entirely against this given that it's a chip feature, so
> > > > the driver should be able to know that it's available.
> > > >
> > > > Dmitri, Wolfram, Jean, any preferences?
> > >
> > > I read this:
> > >
> > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > (that ST microelectronics accelerometer) but due to complicated
> > > HW abstraction and layers on Dell laptops it is handled by two
> > > drivers, one ACPI and one i2c."
> > >
> > > and that is the core of the issue. You have 2 drivers fighting
> > > over the same device. Fix this and it will all work.
> >
> > With my current implementation (which I sent in this patch), they
> > are not fighting.
> >
> > dell-smo8800 exports /dev/freefall (and nothing more) and lis3lv02d
> > only accelerometer device as lis3lv02d driver does not get IRQ
> > number in platform data.
> >
> > > As far as I can see hp_accel instantiates lis3lv02d and accesses
> > > it via ACPI methods, can the same be done for Dell?
> >
> > No, Dell does not have any ACPI methods. And as I wrote in ACPI or
> > DMI is even not i2c address of device, so it needs to be specified
> > in code itself.
> >
> > Really there is no other way... :-(
>
> Sure there is:
>
> 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> 2. dell-smo8800 provides read/write functions for lis3lv02d that
> simply forward requests to dell-smo8800-accel i2c client.
> 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel does.
Sorry, but I do not understand how you mean it... Why to provides new
read/write i2c functions which are already implemented by i2c-i801 bus
and lis3lv02d i2c driver?
> Alternatively, can lis3lv02d be tasked to create /dev/freefall?
If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
device.
But... what is problem with current implementation? Accelerometer HW
provides two functions:
1) 3 axes reports
2) Disk freefall detection
And 1) is handled by i2c driver lis3lv02d and 2) is by dell-smo8800.
Both functions are independent here.
I think you just trying to complicate this situation even more to be
more complicated as currently is.
> Yet another option: can we add a new flag to i2c_board_info
> controlling whether we want to enable/disable wiring up host notify
> interrupt? Benjamin, is there anything "special" in RMI SMbus ACPI
> descriptors we could use?
>
> Thanks.
--
Pali Rohár
pali.rohar@gmail.com
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| From | Dmitry Torokhov <dmitry.torokhov@gmail.com> |
|---|---|
| Date | 2017-01-03 21:40 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVE2e-37A-9@gated-at.bofh.it> |
| In reply to | #1550148 |
On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > wrote:
> > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień wrote:
> > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał Kępień
> > > > > > > > > > wrote:
> > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > 0x29. That i2c address is not specified in DMI
> > > > > > > > > > > > or ACPI, so runtime detection without whitelist
> > > > > > > > > > > > which is below is not possible.
> > > > > > > > > > > >
> > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > address.
> > > > > > > > > > >
> > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > confusing to me at first because there is already
> > > > > > > > > > > an ACPI driver which handles SMO88xx
> > > > > > > > > > >
> > > > > > > > > > > devices (dell-smo8800). My understanding is that:
> > > > > > > > > > > * the purpose of this patch is to expose a richer
> > > > > > > > > > > interface (as
> > > > > > > > > > >
> > > > > > > > > > > provided by lis3lv02d) to these devices on some
> > > > > > > > > > > machines,
> > > > > > > > > > >
> > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > >
> > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > effectively duplicates the work that lis3lv02d
> > > > > > > > > > > does).
> > > > > > > > > >
> > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > exports /dev/freefall device which notify userspace
> > > > > > > > > > about falls. lis3lv02d is i2c driver which exports
> > > > > > > > > > axes of accelerometer. Additionaly lis3lv02d can
> > > > > > > > > > export also /dev/freefall if registerer of i2c
> > > > > > > > > > device provides irq number -- which is not case of
> > > > > > > > > > this patch.
> > > > > > > > > >
> > > > > > > > > > So both drivers are doing different things and both
> > > > > > > > > > are useful.
> > > > > > > > > >
> > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent one HW
> > > > > > > > > > device (that ST microelectronics accelerometer) but
> > > > > > > > > > due to complicated HW abstraction and layers on Dell
> > > > > > > > > > laptops it is handled by two drivers, one ACPI and
> > > > > > > > > > one i2c.
> > > > > > > > > >
> > > > > > > > > > Yes, in ideal world irq number should be passed to
> > > > > > > > > > lis3lv02d driver and that would export whole device
> > > > > > > > > > (with /dev/freefall too), but due to HW abstraction
> > > > > > > > > > it is too much complicated...
> > > > > > > > >
> > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > number all the way down to lis3lv02d is to set the irq
> > > > > > > > > field of the struct i2c_board_info you are passing to
> > > > > > > > > i2c_new_device(). And you can extract that IRQ number
> > > > > > > > > e.g. in check_acpi_smo88xx_device(). However, you would
> > > > > > > > > then need to make sure dell-smo8800 does not attempt to
> > > > > > > > > request the same IRQ on whitelisted machines. This got
> > > > > > > > > me thinking about a way to somehow incorporate your
> > > > > > > > > changes into dell-smo8800 using Wolfram's bus_notifier
> > > > > > > > > suggestion, but I do not have a working solution for
> > > > > > > > > now. What is tempting about this approach is that you
> > > > > > > > > would not have to scan the ACPI namespace in search of
> > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > the one you submitted.
> > > > > > > >
> > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > driver... And there can be some pathological situation
> > > > > > > > (thanks to adding ACPI layer as Andy pointed) that there
> > > > > > > > will be more SMO88xx devices in ACPI. Plus you can
> > > > > > > > compile kernel with and without those modules and also
> > > > > > > > you can blacklist loading them (so compile time check is
> > > > > > > > not enough). And still some correct message notifier
> > > > > > > > must be used.
> > > > > > > >
> > > > > > > > I think such solution is much much more complicated,
> > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > and available dell devices...
> > > > > > >
> > > > > > > I tried a few more things, but ultimately failed to find a
> > > > > > > nice way to implement this.
> > > > > > >
> > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > events, not alert") which breaks your patch. The reason
> > > > > > > for that is that lis3lv02d relies on the i2c client's IRQ
> > > > > > > being 0 to detect that it should not create /dev/freefall.
> > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > causing lis3lv02d to create /dev/freefall, which in turn
> > > > > > > conflicts with dell-smo8800 which is trying to create
> > > > > > > /dev/freefall itself.
> > > > > >
> > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > >
> > > > > Apologies for that.
> > > > >
> > > > > I could easily fix this by adding a kernel API to know whether
> > > > > the provided irq is from Host Notify or if it was coming from
> > > > > an actual declaration. However, I have no idea how many other
> > > > > drivers would require this (hopefully only this one).
> > > > >
> > > > > One other solution would be to reserve the Host Notify IRQ and
> > > > > let the actual drivers that need it to set it, but this was
> > > > > not the best solution according to Dmitri. On my side, I am
> > > > > not entirely against this given that it's a chip feature, so
> > > > > the driver should be able to know that it's available.
> > > > >
> > > > > Dmitri, Wolfram, Jean, any preferences?
> > > >
> > > > I read this:
> > > >
> > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > (that ST microelectronics accelerometer) but due to complicated
> > > > HW abstraction and layers on Dell laptops it is handled by two
> > > > drivers, one ACPI and one i2c."
> > > >
> > > > and that is the core of the issue. You have 2 drivers fighting
> > > > over the same device. Fix this and it will all work.
> > >
> > > With my current implementation (which I sent in this patch), they
> > > are not fighting.
> > >
> > > dell-smo8800 exports /dev/freefall (and nothing more) and lis3lv02d
> > > only accelerometer device as lis3lv02d driver does not get IRQ
> > > number in platform data.
> > >
> > > > As far as I can see hp_accel instantiates lis3lv02d and accesses
> > > > it via ACPI methods, can the same be done for Dell?
> > >
> > > No, Dell does not have any ACPI methods. And as I wrote in ACPI or
> > > DMI is even not i2c address of device, so it needs to be specified
> > > in code itself.
> > >
> > > Really there is no other way... :-(
> >
> > Sure there is:
> >
> > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > simply forward requests to dell-smo8800-accel i2c client.
> > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel does.
>
> Sorry, but I do not understand how you mean it... Why to provides new
> read/write i2c functions which are already implemented by i2c-i801 bus
> and lis3lv02d i2c driver?
Because that would allow you to avoid clashes with i2c creating
interrupt mapping for client residing on host-notify-capable controller.
>
> > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
>
> If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> device.
>
> But... what is problem with current implementation? Accelerometer HW
> provides two functions:
>
> 1) 3 axes reports
> 2) Disk freefall detection
>
> And 1) is handled by i2c driver lis3lv02d and 2) is by dell-smo8800.
> Both functions are independent here.
>
> I think you just trying to complicate this situation even more to be
> more complicated as currently is.
Because this apparently does not work for you, does it? In general, if
you want the same hardware be handled by 2 different drivers you are
going to have bad time.
It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are the
same, right? So, instead of having 2 drivers split the functionality,
can you forego registering smo8800 ACPI driver on your whitelisted
boxes and instead instantiate full i2c client device with properly
assigned both address and IRQ and let lis3lv02d handle it (providing
both accelerometer data and /dev/freefall)?
Thanks.
--
Dmitry
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| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-03 21:50 +0100 |
| Message-ID | <sVEbU-3aT-13@gated-at.bofh.it> |
| In reply to | #1550160 |
[Multipart message — attachments visible in raw view] — view raw
On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > >
> > > > > wrote:
> > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > wrote:
> > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > Kępień
> > > > > > > > > > >
> > > > > > > > > > > wrote:
> > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > address.
> > > > > > > > > > > >
> > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > >
> > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > that:
> > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > richer interface (as
> > > > > > > > > > > >
> > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > some machines,
> > > > > > > > > > > >
> > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > >
> > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > >
> > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > >
> > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > both are useful.
> > > > > > > > > > >
> > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > >
> > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > >
> > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > the one you submitted.
> > > > > > > > >
> > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > driver... And there can be some pathological
> > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > still some correct message notifier must be used.
> > > > > > > > >
> > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > and available dell devices...
> > > > > > > >
> > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > find a nice way to implement this.
> > > > > > > >
> > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > create /dev/freefall.
> > > > > > > >
> > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > >
> > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > create /dev/freefall itself.
> > > > > > >
> > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > >
> > > > > > Apologies for that.
> > > > > >
> > > > > > I could easily fix this by adding a kernel API to know
> > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > coming from an actual declaration. However, I have no idea
> > > > > > how many other drivers would require this (hopefully only
> > > > > > this one).
> > > > > >
> > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > and let the actual drivers that need it to set it, but
> > > > > > this was not the best solution according to Dmitri. On my
> > > > > > side, I am not entirely against this given that it's a
> > > > > > chip feature, so the driver should be able to know that
> > > > > > it's available.
> > > > > >
> > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > >
> > > > > I read this:
> > > > >
> > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > (that ST microelectronics accelerometer) but due to
> > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > handled by two drivers, one ACPI and one i2c."
> > > > >
> > > > > and that is the core of the issue. You have 2 drivers
> > > > > fighting over the same device. Fix this and it will all
> > > > > work.
> > > >
> > > > With my current implementation (which I sent in this patch),
> > > > they are not fighting.
> > > >
> > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > not get IRQ number in platform data.
> > > >
> > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > >
> > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > or DMI is even not i2c address of device, so it needs to be
> > > > specified in code itself.
> > > >
> > > > Really there is no other way... :-(
> > >
> > > Sure there is:
> > >
> > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > simply forward requests to dell-smo8800-accel i2c client.
> > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > does.
> >
> > Sorry, but I do not understand how you mean it... Why to provides
> > new read/write i2c functions which are already implemented by
> > i2c-i801 bus and lis3lv02d i2c driver?
>
> Because that would allow you to avoid clashes with i2c creating
> interrupt mapping for client residing on host-notify-capable
> controller.
>
> > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> >
> > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > device.
> >
> > But... what is problem with current implementation? Accelerometer
> > HW provides two functions:
> >
> > 1) 3 axes reports
> > 2) Disk freefall detection
> >
> > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > dell-smo8800. Both functions are independent here.
> >
> > I think you just trying to complicate this situation even more to
> > be more complicated as currently is.
>
> Because this apparently does not work for you, does it?
It is working fine. I do not see any problem.
> In general,
> if you want the same hardware be handled by 2 different drivers you
> are going to have bad time.
Yes, but in this case half of device is ACPI based and other half i2c
based. This is problem of ACPI and Dell design.
> It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> the same, right?
Yes. I understand that clean solution is to have one driver which
provides everything.
But because half of data are ACPI and half i2c, you still needs to
create two drivers (one ACPI and one i2c). You can put both drivers into
one .ko module, but still these will be two drivers due to how ACPI and
i2c linux abstractions are different.
> So, instead of having 2 drivers split the
> functionality, can you forego registering smo8800 ACPI driver on
> your whitelisted boxes and instead instantiate full i2c client
> device with properly assigned both address and IRQ and let lis3lv02d
> handle it (providing both accelerometer data and /dev/freefall)?
With Michał we already discussed about it, see emails. Basically you can
enable/disable kernel modules at compile time or blacklist at runtime
(or even chose what will be compiled into vmlinux and what as external
.ko module). Some distributions blacklist i2c-i801.ko module... And
there can be also problem with initialization of i2c-i801 driver (fix is
in commit a7ae81952cda, but does not have to work at every time!). So
that move on whitelisted machines can potentially cause disappearance of
/dev/freefall and users will not have hdd protection which is currently
working.
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Dmitry Torokhov <dmitry.torokhov@gmail.com> |
|---|---|
| Date | 2017-01-03 22:10 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVEvg-3xp-23@gated-at.bofh.it> |
| In reply to | #1550169 |
On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > >
> > > > > > wrote:
> > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > wrote:
> > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > Kępień
> > > > > > > > > > > >
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > address.
> > > > > > > > > > > > >
> > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > >
> > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > that:
> > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > >
> > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > some machines,
> > > > > > > > > > > > >
> > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > >
> > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > >
> > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > >
> > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > both are useful.
> > > > > > > > > > > >
> > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > >
> > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > >
> > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > the one you submitted.
> > > > > > > > > >
> > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > >
> > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > and available dell devices...
> > > > > > > > >
> > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > find a nice way to implement this.
> > > > > > > > >
> > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > create /dev/freefall.
> > > > > > > > >
> > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > >
> > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > create /dev/freefall itself.
> > > > > > > >
> > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > >
> > > > > > > Apologies for that.
> > > > > > >
> > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > how many other drivers would require this (hopefully only
> > > > > > > this one).
> > > > > > >
> > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > side, I am not entirely against this given that it's a
> > > > > > > chip feature, so the driver should be able to know that
> > > > > > > it's available.
> > > > > > >
> > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > >
> > > > > > I read this:
> > > > > >
> > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > >
> > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > fighting over the same device. Fix this and it will all
> > > > > > work.
> > > > >
> > > > > With my current implementation (which I sent in this patch),
> > > > > they are not fighting.
> > > > >
> > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > not get IRQ number in platform data.
> > > > >
> > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > >
> > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > specified in code itself.
> > > > >
> > > > > Really there is no other way... :-(
> > > >
> > > > Sure there is:
> > > >
> > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > does.
> > >
> > > Sorry, but I do not understand how you mean it... Why to provides
> > > new read/write i2c functions which are already implemented by
> > > i2c-i801 bus and lis3lv02d i2c driver?
> >
> > Because that would allow you to avoid clashes with i2c creating
> > interrupt mapping for client residing on host-notify-capable
> > controller.
> >
> > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > >
> > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > device.
> > >
> > > But... what is problem with current implementation? Accelerometer
> > > HW provides two functions:
> > >
> > > 1) 3 axes reports
> > > 2) Disk freefall detection
> > >
> > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > dell-smo8800. Both functions are independent here.
> > >
> > > I think you just trying to complicate this situation even more to
> > > be more complicated as currently is.
> >
> > Because this apparently does not work for you, does it?
>
> It is working fine. I do not see any problem.
>
> > In general,
> > if you want the same hardware be handled by 2 different drivers you
> > are going to have bad time.
>
> Yes, but in this case half of device is ACPI based and other half i2c
> based. This is problem of ACPI and Dell design.
>
> > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > the same, right?
>
> Yes. I understand that clean solution is to have one driver which
> provides everything.
>
> But because half of data are ACPI and half i2c, you still needs to
> create two drivers (one ACPI and one i2c). You can put both drivers into
> one .ko module, but still these will be two drivers due to how ACPI and
> i2c linux abstractions are different.
>
> > So, instead of having 2 drivers split the
> > functionality, can you forego registering smo8800 ACPI driver on
> > your whitelisted boxes and instead instantiate full i2c client
> > device with properly assigned both address and IRQ and let lis3lv02d
> > handle it (providing both accelerometer data and /dev/freefall)?
>
> With Michał we already discussed about it, see emails. Basically you can
> enable/disable kernel modules at compile time or blacklist at runtime
> (or even chose what will be compiled into vmlinux and what as external
> .ko module).
This can be solved with a bit of Kconfig/IS_ENABLED() code.
> Some distributions blacklist i2c-i801.ko module... And
Any particular reason for that?
> there can be also problem with initialization of i2c-i801 driver (fix is
> in commit a7ae81952cda, but does not have to work at every time!). So
> that move on whitelisted machines can potentially cause disappearance of
> /dev/freefall and users will not have hdd protection which is currently
> working.
Well, I gave you 2 possible solutions (roll your own i2c read/write,
forward them to i2c client) or have faith in your implementation and let
lis3lv02d handle it.
The 3rd one is to possibly add a flag to disable host notify to IRQ
mapping for given client (if Wolfram/Jean OK with it).
Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
i2c_client with board_info->irq = -1.
Pick whichever you prefer.
By the way, what do you need accelerometer for on these devices? They
don't appear to be tablets that could use one...
Thanks.
--
Dmitry
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 09:20 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVOXD-24Q-11@gated-at.bofh.it> |
| In reply to | #1550193 |
On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > >
> > > > > > > wrote:
> > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > wrote:
> > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > Kępień
> > > > > > > > > > > > >
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > >
> > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > >
> > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > >
> > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > >
> > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > the one you submitted.
> > > > > > > > > > >
> > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > >
> > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > and available dell devices...
> > > > > > > > > >
> > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > find a nice way to implement this.
> > > > > > > > > >
> > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > create /dev/freefall.
> > > > > > > > > >
> > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > >
> > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > create /dev/freefall itself.
> > > > > > > > >
> > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > >
> > > > > > > > Apologies for that.
> > > > > > > >
> > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > this one).
> > > > > > > >
> > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > it's available.
> > > > > > > >
> > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > >
> > > > > > > I read this:
> > > > > > >
> > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > >
> > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > work.
> > > > > >
> > > > > > With my current implementation (which I sent in this patch),
> > > > > > they are not fighting.
> > > > > >
> > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > not get IRQ number in platform data.
> > > > > >
> > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > >
> > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > specified in code itself.
> > > > > >
> > > > > > Really there is no other way... :-(
> > > > >
> > > > > Sure there is:
> > > > >
> > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > does.
> > > >
> > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > new read/write i2c functions which are already implemented by
> > > > i2c-i801 bus and lis3lv02d i2c driver?
> > >
> > > Because that would allow you to avoid clashes with i2c creating
> > > interrupt mapping for client residing on host-notify-capable
> > > controller.
> > >
> > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > >
> > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > device.
> > > >
> > > > But... what is problem with current implementation? Accelerometer
> > > > HW provides two functions:
> > > >
> > > > 1) 3 axes reports
> > > > 2) Disk freefall detection
> > > >
> > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > dell-smo8800. Both functions are independent here.
> > > >
> > > > I think you just trying to complicate this situation even more to
> > > > be more complicated as currently is.
> > >
> > > Because this apparently does not work for you, does it?
> >
> > It is working fine. I do not see any problem.
> >
> > > In general,
> > > if you want the same hardware be handled by 2 different drivers you
> > > are going to have bad time.
> >
> > Yes, but in this case half of device is ACPI based and other half i2c
> > based. This is problem of ACPI and Dell design.
> >
> > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > the same, right?
> >
> > Yes. I understand that clean solution is to have one driver which
> > provides everything.
> >
> > But because half of data are ACPI and half i2c, you still needs to
> > create two drivers (one ACPI and one i2c). You can put both drivers into
> > one .ko module, but still these will be two drivers due to how ACPI and
> > i2c linux abstractions are different.
> >
> > > So, instead of having 2 drivers split the
> > > functionality, can you forego registering smo8800 ACPI driver on
> > > your whitelisted boxes and instead instantiate full i2c client
> > > device with properly assigned both address and IRQ and let lis3lv02d
> > > handle it (providing both accelerometer data and /dev/freefall)?
> >
> > With Michał we already discussed about it, see emails. Basically you can
> > enable/disable kernel modules at compile time or blacklist at runtime
> > (or even chose what will be compiled into vmlinux and what as external
> > .ko module).
>
> This can be solved with a bit of Kconfig/IS_ENABLED() code.
>
> > Some distributions blacklist i2c-i801.ko module... And
>
> Any particular reason for that?
>
> > there can be also problem with initialization of i2c-i801 driver (fix is
> > in commit a7ae81952cda, but does not have to work at every time!). So
> > that move on whitelisted machines can potentially cause disappearance of
> > /dev/freefall and users will not have hdd protection which is currently
> > working.
>
> Well, I gave you 2 possible solutions (roll your own i2c read/write,
> forward them to i2c client) or have faith in your implementation and let
> lis3lv02d handle it.
>
> The 3rd one is to possibly add a flag to disable host notify to IRQ
> mapping for given client (if Wolfram/Jean OK with it).
>
> Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> i2c_client with board_info->irq = -1.
>
> Pick whichever you prefer.
>
> By the way, what do you need accelerometer for on these devices? They
> don't appear to be tablets that could use one...
Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
not work... I thought that discussion is about different mechanism how
to implement bus registration notification to smo8800 driver (or
different solution to not have registration in i801).
--
Pali Rohár
pali.rohar@gmail.com
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| From | Benjamin Tissoires <benjamin.tissoires@redhat.com> |
|---|---|
| Date | 2017-01-04 10:10 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVPK1-2AQ-19@gated-at.bofh.it> |
| In reply to | #1550498 |
On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > >
> > > > > > > > wrote:
> > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > >
> > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > >
> > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > >
> > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > and available dell devices...
> > > > > > > > > > >
> > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > >
> > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > >
> > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > >
> > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > >
> > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > >
> > > > > > > > > Apologies for that.
> > > > > > > > >
> > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > this one).
> > > > > > > > >
> > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > it's available.
> > > > > > > > >
> > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > >
> > > > > > > > I read this:
> > > > > > > >
> > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > >
> > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > work.
> > > > > > >
> > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > they are not fighting.
> > > > > > >
> > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > not get IRQ number in platform data.
> > > > > > >
> > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > >
> > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > specified in code itself.
> > > > > > >
> > > > > > > Really there is no other way... :-(
> > > > > >
> > > > > > Sure there is:
> > > > > >
> > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > does.
> > > > >
> > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > new read/write i2c functions which are already implemented by
> > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > >
> > > > Because that would allow you to avoid clashes with i2c creating
> > > > interrupt mapping for client residing on host-notify-capable
> > > > controller.
> > > >
> > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > >
> > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > device.
> > > > >
> > > > > But... what is problem with current implementation? Accelerometer
> > > > > HW provides two functions:
> > > > >
> > > > > 1) 3 axes reports
> > > > > 2) Disk freefall detection
> > > > >
> > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > dell-smo8800. Both functions are independent here.
> > > > >
> > > > > I think you just trying to complicate this situation even more to
> > > > > be more complicated as currently is.
> > > >
> > > > Because this apparently does not work for you, does it?
> > >
> > > It is working fine. I do not see any problem.
> > >
> > > > In general,
> > > > if you want the same hardware be handled by 2 different drivers you
> > > > are going to have bad time.
> > >
> > > Yes, but in this case half of device is ACPI based and other half i2c
> > > based. This is problem of ACPI and Dell design.
> > >
> > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > the same, right?
> > >
> > > Yes. I understand that clean solution is to have one driver which
> > > provides everything.
> > >
> > > But because half of data are ACPI and half i2c, you still needs to
> > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > one .ko module, but still these will be two drivers due to how ACPI and
> > > i2c linux abstractions are different.
> > >
> > > > So, instead of having 2 drivers split the
> > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > your whitelisted boxes and instead instantiate full i2c client
> > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > handle it (providing both accelerometer data and /dev/freefall)?
> > >
> > > With Michał we already discussed about it, see emails. Basically you can
> > > enable/disable kernel modules at compile time or blacklist at runtime
> > > (or even chose what will be compiled into vmlinux and what as external
> > > .ko module).
> >
> > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> >
> > > Some distributions blacklist i2c-i801.ko module... And
> >
> > Any particular reason for that?
> >
> > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > that move on whitelisted machines can potentially cause disappearance of
> > > /dev/freefall and users will not have hdd protection which is currently
> > > working.
> >
> > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > forward them to i2c client) or have faith in your implementation and let
> > lis3lv02d handle it.
> >
> > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > mapping for given client (if Wolfram/Jean OK with it).
> >
> > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > i2c_client with board_info->irq = -1.
> >
> > Pick whichever you prefer.
> >
> > By the way, what do you need accelerometer for on these devices? They
> > don't appear to be tablets that could use one...
>
> Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> not work... I thought that discussion is about different mechanism how
> to implement bus registration notification to smo8800 driver (or
> different solution to not have registration in i801).
>
Just because I am not sure I got everything right, could you confirm
that:
- in the current upstream tree, the dell-smo8800 driver is now broken
after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
alert)
- this series adds an extra lis3lv02d on some machines and you have
problem fighting for the irq (but this is not upstream yet). The extra
lis3lv02d node is added from dell-smo8800
If the first point is not correct (by default, dell-smo8800 will not be
loaded at the same time than lis3lv02d), then it's a design issue with
the interactions between those 2 drivers.
If the first point is correct because ACPI declares both devices, then
there is an urgent fix to propose to not enable Host Notify by default
on Host Notifier capable adapters. (even though the design between the
2 drivers is wrong, it's considered as a regression).
Cheers,
Benjamin
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 10:20 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVPTI-2FK-31@gated-at.bofh.it> |
| In reply to | #1550539 |
On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > >
> > > > > > > > > wrote:
> > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > >
> > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > >
> > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > >
> > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > >
> > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > >
> > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > >
> > > > > > > > > > Apologies for that.
> > > > > > > > > >
> > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > this one).
> > > > > > > > > >
> > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > it's available.
> > > > > > > > > >
> > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > >
> > > > > > > > > I read this:
> > > > > > > > >
> > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > >
> > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > work.
> > > > > > > >
> > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > they are not fighting.
> > > > > > > >
> > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > not get IRQ number in platform data.
> > > > > > > >
> > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > >
> > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > specified in code itself.
> > > > > > > >
> > > > > > > > Really there is no other way... :-(
> > > > > > >
> > > > > > > Sure there is:
> > > > > > >
> > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > does.
> > > > > >
> > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > new read/write i2c functions which are already implemented by
> > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > >
> > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > interrupt mapping for client residing on host-notify-capable
> > > > > controller.
> > > > >
> > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > >
> > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > device.
> > > > > >
> > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > HW provides two functions:
> > > > > >
> > > > > > 1) 3 axes reports
> > > > > > 2) Disk freefall detection
> > > > > >
> > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > dell-smo8800. Both functions are independent here.
> > > > > >
> > > > > > I think you just trying to complicate this situation even more to
> > > > > > be more complicated as currently is.
> > > > >
> > > > > Because this apparently does not work for you, does it?
> > > >
> > > > It is working fine. I do not see any problem.
> > > >
> > > > > In general,
> > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > are going to have bad time.
> > > >
> > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > based. This is problem of ACPI and Dell design.
> > > >
> > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > the same, right?
> > > >
> > > > Yes. I understand that clean solution is to have one driver which
> > > > provides everything.
> > > >
> > > > But because half of data are ACPI and half i2c, you still needs to
> > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > i2c linux abstractions are different.
> > > >
> > > > > So, instead of having 2 drivers split the
> > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > >
> > > > With Michał we already discussed about it, see emails. Basically you can
> > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > (or even chose what will be compiled into vmlinux and what as external
> > > > .ko module).
> > >
> > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > >
> > > > Some distributions blacklist i2c-i801.ko module... And
> > >
> > > Any particular reason for that?
> > >
> > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > that move on whitelisted machines can potentially cause disappearance of
> > > > /dev/freefall and users will not have hdd protection which is currently
> > > > working.
> > >
> > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > forward them to i2c client) or have faith in your implementation and let
> > > lis3lv02d handle it.
> > >
> > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > mapping for given client (if Wolfram/Jean OK with it).
> > >
> > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > i2c_client with board_info->irq = -1.
> > >
> > > Pick whichever you prefer.
> > >
> > > By the way, what do you need accelerometer for on these devices? They
> > > don't appear to be tablets that could use one...
> >
> > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > not work... I thought that discussion is about different mechanism how
> > to implement bus registration notification to smo8800 driver (or
> > different solution to not have registration in i801).
> >
>
> Just because I am not sure I got everything right, could you confirm
> that:
> - in the current upstream tree, the dell-smo8800 driver is now broken
> after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> alert)
No, dell-smo8800 it is working fine. It is fully independent from i2c
and lis3lv02d. It is pure ACPI driver which does not share anything with
i2c.
> - this series adds an extra lis3lv02d on some machines and you have
> problem fighting for the irq (but this is not upstream yet).
Yes, this series (not merged yet) adds extra lis3lv02d device but is not
working because of 4d5538f5882a.
> The extra lis3lv02d node is added from dell-smo8800
No, dell-smo8800 does not add new node in this patch.
> If the first point is not correct (by default, dell-smo8800 will not be
> loaded at the same time than lis3lv02d), then it's a design issue with
> the interactions between those 2 drivers.
No, there is no interactions between these two drivers (dell-smo8800 and
lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
/dev/freefall device based on IRQ (and nothing more).
And lis3lv02d in *current* configuration in this patch exports only
accelerometer input device, not /dev/freefall. It does not use IRQ.
(Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
number which is not freefall report, therefore lis3lv02d does not work).
To make it clear, ST Accelerometer provides two operations:
* report free fall
* report 3 axes
Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
lis3lv02d can handle also free fall IRQ is platform i2c data provides
IRQ number for it -- but this is not case in our Dell configuration. But
commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
not free fall detection and so is breaking lis3lv02 driver. In our Dell
configuration (by this patch) there should be no IRQ number.
It is clear now?
> If the first point is correct because ACPI declares both devices, then
> there is an urgent fix to propose to not enable Host Notify by default
> on Host Notifier capable adapters. (even though the design between the
> 2 drivers is wrong, it's considered as a regression).
>
> Cheers,
> Benjamin
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Benjamin Tissoires <benjamin.tissoires@redhat.com> |
|---|---|
| Date | 2017-01-04 11:20 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVQPL-3lt-1@gated-at.bofh.it> |
| In reply to | #1550559 |
On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > >
> > > > > > > > > > wrote:
> > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > >
> > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > >
> > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > >
> > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > >
> > > > > > > > > > > Apologies for that.
> > > > > > > > > > >
> > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > this one).
> > > > > > > > > > >
> > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > it's available.
> > > > > > > > > > >
> > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > >
> > > > > > > > > > I read this:
> > > > > > > > > >
> > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > >
> > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > work.
> > > > > > > > >
> > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > they are not fighting.
> > > > > > > > >
> > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > not get IRQ number in platform data.
> > > > > > > > >
> > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > >
> > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > specified in code itself.
> > > > > > > > >
> > > > > > > > > Really there is no other way... :-(
> > > > > > > >
> > > > > > > > Sure there is:
> > > > > > > >
> > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > does.
> > > > > > >
> > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > >
> > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > controller.
> > > > > >
> > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > >
> > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > device.
> > > > > > >
> > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > HW provides two functions:
> > > > > > >
> > > > > > > 1) 3 axes reports
> > > > > > > 2) Disk freefall detection
> > > > > > >
> > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > >
> > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > be more complicated as currently is.
> > > > > >
> > > > > > Because this apparently does not work for you, does it?
> > > > >
> > > > > It is working fine. I do not see any problem.
> > > > >
> > > > > > In general,
> > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > are going to have bad time.
> > > > >
> > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > based. This is problem of ACPI and Dell design.
> > > > >
> > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > the same, right?
> > > > >
> > > > > Yes. I understand that clean solution is to have one driver which
> > > > > provides everything.
> > > > >
> > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > i2c linux abstractions are different.
> > > > >
> > > > > > So, instead of having 2 drivers split the
> > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > >
> > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > .ko module).
> > > >
> > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > >
> > > > > Some distributions blacklist i2c-i801.ko module... And
> > > >
> > > > Any particular reason for that?
> > > >
> > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > working.
> > > >
> > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > forward them to i2c client) or have faith in your implementation and let
> > > > lis3lv02d handle it.
> > > >
> > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > mapping for given client (if Wolfram/Jean OK with it).
> > > >
> > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > i2c_client with board_info->irq = -1.
> > > >
> > > > Pick whichever you prefer.
> > > >
> > > > By the way, what do you need accelerometer for on these devices? They
> > > > don't appear to be tablets that could use one...
> > >
> > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > not work... I thought that discussion is about different mechanism how
> > > to implement bus registration notification to smo8800 driver (or
> > > different solution to not have registration in i801).
> > >
> >
> > Just because I am not sure I got everything right, could you confirm
> > that:
> > - in the current upstream tree, the dell-smo8800 driver is now broken
> > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > alert)
>
> No, dell-smo8800 it is working fine. It is fully independent from i2c
> and lis3lv02d. It is pure ACPI driver which does not share anything with
> i2c.
>
> > - this series adds an extra lis3lv02d on some machines and you have
> > problem fighting for the irq (but this is not upstream yet).
>
> Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> working because of 4d5538f5882a.
>
> > The extra lis3lv02d node is added from dell-smo8800
>
> No, dell-smo8800 does not add new node in this patch.
>
> > If the first point is not correct (by default, dell-smo8800 will not be
> > loaded at the same time than lis3lv02d), then it's a design issue with
> > the interactions between those 2 drivers.
>
> No, there is no interactions between these two drivers (dell-smo8800 and
> lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> /dev/freefall device based on IRQ (and nothing more).
>
> And lis3lv02d in *current* configuration in this patch exports only
> accelerometer input device, not /dev/freefall. It does not use IRQ.
> (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> number which is not freefall report, therefore lis3lv02d does not work).
>
> To make it clear, ST Accelerometer provides two operations:
> * report free fall
> * report 3 axes
>
> Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
>
> lis3lv02d can handle also free fall IRQ is platform i2c data provides
> IRQ number for it -- but this is not case in our Dell configuration. But
> commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> not free fall detection and so is breaking lis3lv02 driver. In our Dell
> configuration (by this patch) there should be no IRQ number.
>
> It is clear now?
I think I am starting to understand the problem.
Currently (upstream tree), 4d5538f5882a doesn't break anything. On the
mentioned Dell platforms, the dell-smo8800 gets loaded and provides
/dev/freefall. lis3lv02d is not loaded so everything just works.
The problem comes from this patch which doesn't set the irq in
i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
in i2c_board_info in your patch and only forward it to
lis3lv02d_init_device() only if it is positive (valid).
So, to me 4d5538f5882a doesn't introduce a regression so we should keep
it in its current state.
Cheers,
Benjamin
>
> > If the first point is correct because ACPI declares both devices, then
> > there is an urgent fix to propose to not enable Host Notify by default
> > on Host Notifier capable adapters. (even though the design between the
> > 2 drivers is wrong, it's considered as a regression).
> >
> > Cheers,
> > Benjamin
>
> --
> Pali Rohár
> pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 11:30 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVQZr-3pc-7@gated-at.bofh.it> |
| In reply to | #1550606 |
On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > >
> > > > > > > > > > > wrote:
> > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > >
> > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > >
> > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > >
> > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > this one).
> > > > > > > > > > > >
> > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > it's available.
> > > > > > > > > > > >
> > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > >
> > > > > > > > > > > I read this:
> > > > > > > > > > >
> > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > >
> > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > work.
> > > > > > > > > >
> > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > they are not fighting.
> > > > > > > > > >
> > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > >
> > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > >
> > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > specified in code itself.
> > > > > > > > > >
> > > > > > > > > > Really there is no other way... :-(
> > > > > > > > >
> > > > > > > > > Sure there is:
> > > > > > > > >
> > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > does.
> > > > > > > >
> > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > >
> > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > controller.
> > > > > > >
> > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > >
> > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > device.
> > > > > > > >
> > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > HW provides two functions:
> > > > > > > >
> > > > > > > > 1) 3 axes reports
> > > > > > > > 2) Disk freefall detection
> > > > > > > >
> > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > >
> > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > be more complicated as currently is.
> > > > > > >
> > > > > > > Because this apparently does not work for you, does it?
> > > > > >
> > > > > > It is working fine. I do not see any problem.
> > > > > >
> > > > > > > In general,
> > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > are going to have bad time.
> > > > > >
> > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > based. This is problem of ACPI and Dell design.
> > > > > >
> > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > the same, right?
> > > > > >
> > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > provides everything.
> > > > > >
> > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > i2c linux abstractions are different.
> > > > > >
> > > > > > > So, instead of having 2 drivers split the
> > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > >
> > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > .ko module).
> > > > >
> > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > >
> > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > >
> > > > > Any particular reason for that?
> > > > >
> > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > working.
> > > > >
> > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > lis3lv02d handle it.
> > > > >
> > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > >
> > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > i2c_client with board_info->irq = -1.
> > > > >
> > > > > Pick whichever you prefer.
> > > > >
> > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > don't appear to be tablets that could use one...
> > > >
> > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > not work... I thought that discussion is about different mechanism how
> > > > to implement bus registration notification to smo8800 driver (or
> > > > different solution to not have registration in i801).
> > > >
> > >
> > > Just because I am not sure I got everything right, could you confirm
> > > that:
> > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > alert)
> >
> > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > i2c.
> >
> > > - this series adds an extra lis3lv02d on some machines and you have
> > > problem fighting for the irq (but this is not upstream yet).
> >
> > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > working because of 4d5538f5882a.
> >
> > > The extra lis3lv02d node is added from dell-smo8800
> >
> > No, dell-smo8800 does not add new node in this patch.
> >
> > > If the first point is not correct (by default, dell-smo8800 will not be
> > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > the interactions between those 2 drivers.
> >
> > No, there is no interactions between these two drivers (dell-smo8800 and
> > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > /dev/freefall device based on IRQ (and nothing more).
> >
> > And lis3lv02d in *current* configuration in this patch exports only
> > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > number which is not freefall report, therefore lis3lv02d does not work).
> >
> > To make it clear, ST Accelerometer provides two operations:
> > * report free fall
> > * report 3 axes
> >
> > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> >
> > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > IRQ number for it -- but this is not case in our Dell configuration. But
> > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > configuration (by this patch) there should be no IRQ number.
> >
> > It is clear now?
>
> I think I am starting to understand the problem.
>
> Currently (upstream tree), 4d5538f5882a doesn't break anything.
I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
(missing = no freefall) and there could be already hardware/boards which
register lis3lv02d i2c device without IRQ number. And definitions could
be also in device tree and so outside of kernel sources...
So there can be potentially break. But at least not case of Dell.
> On the
> mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> /dev/freefall. lis3lv02d is not loaded so everything just works.
Yes.
> The problem comes from this patch which doesn't set the irq in
> i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> in i2c_board_info in your patch and only forward it to
> lis3lv02d_init_device() only if it is positive (valid).
Now I understood that Dmitri means. For this Dell platforms it is OK,
but we have a problem for device tree platforms. Normally in device tree
if device does not support something you just do not specify it. But
with this approach you need to explicitly specify IRQ to -1 in device
tree. And I think this is really not a clean solution.
> So, to me 4d5538f5882a doesn't introduce a regression so we should keep
> it in its current state.
>
> Cheers,
> Benjamin
>
> >
> > > If the first point is correct because ACPI declares both devices, then
> > > there is an urgent fix to propose to not enable Host Notify by default
> > > on Host Notifier capable adapters. (even though the design between the
> > > 2 drivers is wrong, it's considered as a regression).
> > >
> > > Cheers,
> > > Benjamin
> >
> > --
> > Pali Rohár
> > pali.rohar@gmail.com
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Benjamin Tissoires <benjamin.tissoires@redhat.com> |
|---|---|
| Date | 2017-01-04 11:40 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVR98-3si-5@gated-at.bofh.it> |
| In reply to | #1550618 |
On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > > >
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > > >
> > > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > > this one).
> > > > > > > > > > > > >
> > > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > > it's available.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > > >
> > > > > > > > > > > > I read this:
> > > > > > > > > > > >
> > > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > > >
> > > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > > work.
> > > > > > > > > > >
> > > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > > they are not fighting.
> > > > > > > > > > >
> > > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > > >
> > > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > > >
> > > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > > specified in code itself.
> > > > > > > > > > >
> > > > > > > > > > > Really there is no other way... :-(
> > > > > > > > > >
> > > > > > > > > > Sure there is:
> > > > > > > > > >
> > > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > > does.
> > > > > > > > >
> > > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > > >
> > > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > > controller.
> > > > > > > >
> > > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > > >
> > > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > > device.
> > > > > > > > >
> > > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > > HW provides two functions:
> > > > > > > > >
> > > > > > > > > 1) 3 axes reports
> > > > > > > > > 2) Disk freefall detection
> > > > > > > > >
> > > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > > >
> > > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > > be more complicated as currently is.
> > > > > > > >
> > > > > > > > Because this apparently does not work for you, does it?
> > > > > > >
> > > > > > > It is working fine. I do not see any problem.
> > > > > > >
> > > > > > > > In general,
> > > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > > are going to have bad time.
> > > > > > >
> > > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > > based. This is problem of ACPI and Dell design.
> > > > > > >
> > > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > > the same, right?
> > > > > > >
> > > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > > provides everything.
> > > > > > >
> > > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > > i2c linux abstractions are different.
> > > > > > >
> > > > > > > > So, instead of having 2 drivers split the
> > > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > > >
> > > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > > .ko module).
> > > > > >
> > > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > > >
> > > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > > >
> > > > > > Any particular reason for that?
> > > > > >
> > > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > > working.
> > > > > >
> > > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > > lis3lv02d handle it.
> > > > > >
> > > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > > >
> > > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > > i2c_client with board_info->irq = -1.
> > > > > >
> > > > > > Pick whichever you prefer.
> > > > > >
> > > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > > don't appear to be tablets that could use one...
> > > > >
> > > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > > not work... I thought that discussion is about different mechanism how
> > > > > to implement bus registration notification to smo8800 driver (or
> > > > > different solution to not have registration in i801).
> > > > >
> > > >
> > > > Just because I am not sure I got everything right, could you confirm
> > > > that:
> > > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > > alert)
> > >
> > > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > > i2c.
> > >
> > > > - this series adds an extra lis3lv02d on some machines and you have
> > > > problem fighting for the irq (but this is not upstream yet).
> > >
> > > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > > working because of 4d5538f5882a.
> > >
> > > > The extra lis3lv02d node is added from dell-smo8800
> > >
> > > No, dell-smo8800 does not add new node in this patch.
> > >
> > > > If the first point is not correct (by default, dell-smo8800 will not be
> > > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > > the interactions between those 2 drivers.
> > >
> > > No, there is no interactions between these two drivers (dell-smo8800 and
> > > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > > /dev/freefall device based on IRQ (and nothing more).
> > >
> > > And lis3lv02d in *current* configuration in this patch exports only
> > > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > > number which is not freefall report, therefore lis3lv02d does not work).
> > >
> > > To make it clear, ST Accelerometer provides two operations:
> > > * report free fall
> > > * report 3 axes
> > >
> > > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> > >
> > > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > > IRQ number for it -- but this is not case in our Dell configuration. But
> > > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > > configuration (by this patch) there should be no IRQ number.
> > >
> > > It is clear now?
> >
> > I think I am starting to understand the problem.
> >
> > Currently (upstream tree), 4d5538f5882a doesn't break anything.
>
> I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
> (missing = no freefall) and there could be already hardware/boards which
> register lis3lv02d i2c device without IRQ number. And definitions could
> be also in device tree and so outside of kernel sources...
>
> So there can be potentially break. But at least not case of Dell.
>
> > On the
> > mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> > /dev/freefall. lis3lv02d is not loaded so everything just works.
>
> Yes.
>
> > The problem comes from this patch which doesn't set the irq in
> > i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> > Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> > in i2c_board_info in your patch and only forward it to
> > lis3lv02d_init_device() only if it is positive (valid).
>
> Now I understood that Dmitri means. For this Dell platforms it is OK,
> but we have a problem for device tree platforms. Normally in device tree
> if device does not support something you just do not specify it. But
> with this approach you need to explicitly specify IRQ to -1 in device
> tree. And I think this is really not a clean solution.
>
No. DT platforms won't have an issue: they don't change anything, and
there will be a new /dev/freefall misc device for the platforms that
don't have the irq set *and* if the device is on a Host Notify capable
adapter, currently only i2c-i801. But given that they are DT and not
ACPI, this won't conflict with dell-smo8800, so there won't be any
errors, just a dangling unused device node.
This approach is IMO the best if you want to have this in the kernel.
Cheers,
Benjamin
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 12:30 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVRVv-41i-11@gated-at.bofh.it> |
| In reply to | #1550642 |
On Wednesday 04 January 2017 11:32:33 Benjamin Tissoires wrote:
> On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > > > >
> > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > > > this one).
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > > > it's available.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > > > >
> > > > > > > > > > > > > I read this:
> > > > > > > > > > > > >
> > > > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > > > >
> > > > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > > > work.
> > > > > > > > > > > >
> > > > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > > > they are not fighting.
> > > > > > > > > > > >
> > > > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > > > >
> > > > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > > > >
> > > > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > > > specified in code itself.
> > > > > > > > > > > >
> > > > > > > > > > > > Really there is no other way... :-(
> > > > > > > > > > >
> > > > > > > > > > > Sure there is:
> > > > > > > > > > >
> > > > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > > > does.
> > > > > > > > > >
> > > > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > > > >
> > > > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > > > controller.
> > > > > > > > >
> > > > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > > > >
> > > > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > > > device.
> > > > > > > > > >
> > > > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > > > HW provides two functions:
> > > > > > > > > >
> > > > > > > > > > 1) 3 axes reports
> > > > > > > > > > 2) Disk freefall detection
> > > > > > > > > >
> > > > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > > > >
> > > > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > > > be more complicated as currently is.
> > > > > > > > >
> > > > > > > > > Because this apparently does not work for you, does it?
> > > > > > > >
> > > > > > > > It is working fine. I do not see any problem.
> > > > > > > >
> > > > > > > > > In general,
> > > > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > > > are going to have bad time.
> > > > > > > >
> > > > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > > > based. This is problem of ACPI and Dell design.
> > > > > > > >
> > > > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > > > the same, right?
> > > > > > > >
> > > > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > > > provides everything.
> > > > > > > >
> > > > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > > > i2c linux abstractions are different.
> > > > > > > >
> > > > > > > > > So, instead of having 2 drivers split the
> > > > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > > > >
> > > > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > > > .ko module).
> > > > > > >
> > > > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > > > >
> > > > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > > > >
> > > > > > > Any particular reason for that?
> > > > > > >
> > > > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > > > working.
> > > > > > >
> > > > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > > > lis3lv02d handle it.
> > > > > > >
> > > > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > > > >
> > > > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > > > i2c_client with board_info->irq = -1.
> > > > > > >
> > > > > > > Pick whichever you prefer.
> > > > > > >
> > > > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > > > don't appear to be tablets that could use one...
> > > > > >
> > > > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > > > not work... I thought that discussion is about different mechanism how
> > > > > > to implement bus registration notification to smo8800 driver (or
> > > > > > different solution to not have registration in i801).
> > > > > >
> > > > >
> > > > > Just because I am not sure I got everything right, could you confirm
> > > > > that:
> > > > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > > > alert)
> > > >
> > > > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > > > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > > > i2c.
> > > >
> > > > > - this series adds an extra lis3lv02d on some machines and you have
> > > > > problem fighting for the irq (but this is not upstream yet).
> > > >
> > > > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > > > working because of 4d5538f5882a.
> > > >
> > > > > The extra lis3lv02d node is added from dell-smo8800
> > > >
> > > > No, dell-smo8800 does not add new node in this patch.
> > > >
> > > > > If the first point is not correct (by default, dell-smo8800 will not be
> > > > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > > > the interactions between those 2 drivers.
> > > >
> > > > No, there is no interactions between these two drivers (dell-smo8800 and
> > > > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > > > /dev/freefall device based on IRQ (and nothing more).
> > > >
> > > > And lis3lv02d in *current* configuration in this patch exports only
> > > > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > > > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > > > number which is not freefall report, therefore lis3lv02d does not work).
> > > >
> > > > To make it clear, ST Accelerometer provides two operations:
> > > > * report free fall
> > > > * report 3 axes
> > > >
> > > > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > > > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> > > >
> > > > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > > > IRQ number for it -- but this is not case in our Dell configuration. But
> > > > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > > > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > > > configuration (by this patch) there should be no IRQ number.
> > > >
> > > > It is clear now?
> > >
> > > I think I am starting to understand the problem.
> > >
> > > Currently (upstream tree), 4d5538f5882a doesn't break anything.
> >
> > I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
> > (missing = no freefall) and there could be already hardware/boards which
> > register lis3lv02d i2c device without IRQ number. And definitions could
> > be also in device tree and so outside of kernel sources...
> >
> > So there can be potentially break. But at least not case of Dell.
> >
> > > On the
> > > mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> > > /dev/freefall. lis3lv02d is not loaded so everything just works.
> >
> > Yes.
> >
> > > The problem comes from this patch which doesn't set the irq in
> > > i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> > > Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> > > in i2c_board_info in your patch and only forward it to
> > > lis3lv02d_init_device() only if it is positive (valid).
> >
> > Now I understood that Dmitri means. For this Dell platforms it is OK,
> > but we have a problem for device tree platforms. Normally in device tree
> > if device does not support something you just do not specify it. But
> > with this approach you need to explicitly specify IRQ to -1 in device
> > tree. And I think this is really not a clean solution.
> >
Here I was talking about other platforms/devices (not this Dell one).
> No. DT platforms won't have an issue: they don't change anything, and
> there will be a new /dev/freefall misc device for the platforms that
And this is wrong! There should not be any /dev/freefall device
connected with signal host notify. /dev/freefall is for hardware which
supports free fall hdd detection.
> don't have the irq set *and* if the device is on a Host Notify capable
> adapter, currently only i2c-i801.
I understood, but in future more bus drivers could support host notify.
This is basically incorrect if we use one property for two different
things (host notify and hdd free fall).
For me it looks like that we should separate these two things into two
IRQ properties. It is really wrong design if one property is used for
two different things.
> But given that they are DT and not
> ACPI, this won't conflict with dell-smo8800, so there won't be any
> errors, just a dangling unused device node.
Yes, for upcoming Dell in this patch (with IRQ -1) it is not a problem.
> This approach is IMO the best if you want to have this in the kernel.
>
> Cheers,
> Benjamin
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 13:10 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVSyd-4tG-3@gated-at.bofh.it> |
| In reply to | #1550673 |
On Wednesday 04 January 2017 12:22:23 Pali Rohár wrote:
> On Wednesday 04 January 2017 11:32:33 Benjamin Tissoires wrote:
> > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > > > > this one).
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > > > > it's available.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I read this:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > > > > work.
> > > > > > > > > > > > >
> > > > > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > > > > they are not fighting.
> > > > > > > > > > > > >
> > > > > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > > > > >
> > > > > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > > > > >
> > > > > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > > > > specified in code itself.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Really there is no other way... :-(
> > > > > > > > > > > >
> > > > > > > > > > > > Sure there is:
> > > > > > > > > > > >
> > > > > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > > > > does.
> > > > > > > > > > >
> > > > > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > > > > >
> > > > > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > > > > controller.
> > > > > > > > > >
> > > > > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > > > > >
> > > > > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > > > > device.
> > > > > > > > > > >
> > > > > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > > > > HW provides two functions:
> > > > > > > > > > >
> > > > > > > > > > > 1) 3 axes reports
> > > > > > > > > > > 2) Disk freefall detection
> > > > > > > > > > >
> > > > > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > > > > >
> > > > > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > > > > be more complicated as currently is.
> > > > > > > > > >
> > > > > > > > > > Because this apparently does not work for you, does it?
> > > > > > > > >
> > > > > > > > > It is working fine. I do not see any problem.
> > > > > > > > >
> > > > > > > > > > In general,
> > > > > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > > > > are going to have bad time.
> > > > > > > > >
> > > > > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > > > > based. This is problem of ACPI and Dell design.
> > > > > > > > >
> > > > > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > > > > the same, right?
> > > > > > > > >
> > > > > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > > > > provides everything.
> > > > > > > > >
> > > > > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > > > > i2c linux abstractions are different.
> > > > > > > > >
> > > > > > > > > > So, instead of having 2 drivers split the
> > > > > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > > > > >
> > > > > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > > > > .ko module).
> > > > > > > >
> > > > > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > > > > >
> > > > > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > > > > >
> > > > > > > > Any particular reason for that?
> > > > > > > >
> > > > > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > > > > working.
> > > > > > > >
> > > > > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > > > > lis3lv02d handle it.
> > > > > > > >
> > > > > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > > > > >
> > > > > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > > > > i2c_client with board_info->irq = -1.
> > > > > > > >
> > > > > > > > Pick whichever you prefer.
> > > > > > > >
> > > > > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > > > > don't appear to be tablets that could use one...
> > > > > > >
> > > > > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > > > > not work... I thought that discussion is about different mechanism how
> > > > > > > to implement bus registration notification to smo8800 driver (or
> > > > > > > different solution to not have registration in i801).
> > > > > > >
> > > > > >
> > > > > > Just because I am not sure I got everything right, could you confirm
> > > > > > that:
> > > > > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > > > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > > > > alert)
> > > > >
> > > > > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > > > > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > > > > i2c.
> > > > >
> > > > > > - this series adds an extra lis3lv02d on some machines and you have
> > > > > > problem fighting for the irq (but this is not upstream yet).
> > > > >
> > > > > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > > > > working because of 4d5538f5882a.
> > > > >
> > > > > > The extra lis3lv02d node is added from dell-smo8800
> > > > >
> > > > > No, dell-smo8800 does not add new node in this patch.
> > > > >
> > > > > > If the first point is not correct (by default, dell-smo8800 will not be
> > > > > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > > > > the interactions between those 2 drivers.
> > > > >
> > > > > No, there is no interactions between these two drivers (dell-smo8800 and
> > > > > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > > > > /dev/freefall device based on IRQ (and nothing more).
> > > > >
> > > > > And lis3lv02d in *current* configuration in this patch exports only
> > > > > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > > > > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > > > > number which is not freefall report, therefore lis3lv02d does not work).
> > > > >
> > > > > To make it clear, ST Accelerometer provides two operations:
> > > > > * report free fall
> > > > > * report 3 axes
> > > > >
> > > > > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > > > > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> > > > >
> > > > > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > > > > IRQ number for it -- but this is not case in our Dell configuration. But
> > > > > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > > > > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > > > > configuration (by this patch) there should be no IRQ number.
> > > > >
> > > > > It is clear now?
> > > >
> > > > I think I am starting to understand the problem.
> > > >
> > > > Currently (upstream tree), 4d5538f5882a doesn't break anything.
> > >
> > > I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
> > > (missing = no freefall) and there could be already hardware/boards which
> > > register lis3lv02d i2c device without IRQ number. And definitions could
> > > be also in device tree and so outside of kernel sources...
> > >
> > > So there can be potentially break. But at least not case of Dell.
> > >
> > > > On the
> > > > mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> > > > /dev/freefall. lis3lv02d is not loaded so everything just works.
> > >
> > > Yes.
> > >
> > > > The problem comes from this patch which doesn't set the irq in
> > > > i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> > > > Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> > > > in i2c_board_info in your patch and only forward it to
> > > > lis3lv02d_init_device() only if it is positive (valid).
> > >
> > > Now I understood that Dmitri means. For this Dell platforms it is OK,
> > > but we have a problem for device tree platforms. Normally in device tree
> > > if device does not support something you just do not specify it. But
> > > with this approach you need to explicitly specify IRQ to -1 in device
> > > tree. And I think this is really not a clean solution.
> > >
>
> Here I was talking about other platforms/devices (not this Dell one).
>
> > No. DT platforms won't have an issue: they don't change anything, and
> > there will be a new /dev/freefall misc device for the platforms that
>
> And this is wrong! There should not be any /dev/freefall device
> connected with signal host notify. /dev/freefall is for hardware which
> supports free fall hdd detection.
>
> > don't have the irq set *and* if the device is on a Host Notify capable
> > adapter, currently only i2c-i801.
>
> I understood, but in future more bus drivers could support host notify.
This is really fragile. lis3lv02d will empty IRQ (0) will work on some
i2c buses and on some not. I would really expect that i2c driver
(lis3lv02d) will work in same way with any i2c bus driver. And not that
on i801 will acts differently as on e.g. omap3 i2c bus.
> This is basically incorrect if we use one property for two different
> things (host notify and hdd free fall).
>
> For me it looks like that we should separate these two things into two
> IRQ properties. It is really wrong design if one property is used for
> two different things.
>
> > But given that they are DT and not
> > ACPI, this won't conflict with dell-smo8800, so there won't be any
> > errors, just a dangling unused device node.
>
> Yes, for upcoming Dell in this patch (with IRQ -1) it is not a problem.
>
> > This approach is IMO the best if you want to have this in the kernel.
> >
> > Cheers,
> > Benjamin
>
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Benjamin Tissoires <benjamin.tissoires@redhat.com> |
|---|---|
| Date | 2017-01-04 14:10 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVTui-55P-45@gated-at.bofh.it> |
| In reply to | #1550700 |
On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> On Wednesday 04 January 2017 12:22:23 Pali Rohár wrote:
> > On Wednesday 04 January 2017 11:32:33 Benjamin Tissoires wrote:
> > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > > > > > this one).
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > > > > > it's available.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I read this:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > > > > > work.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > > > > > they are not fighting.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > > > > > specified in code itself.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Really there is no other way... :-(
> > > > > > > > > > > > >
> > > > > > > > > > > > > Sure there is:
> > > > > > > > > > > > >
> > > > > > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > > > > > does.
> > > > > > > > > > > >
> > > > > > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > > > > > >
> > > > > > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > > > > > controller.
> > > > > > > > > > >
> > > > > > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > > > > > >
> > > > > > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > > > > > device.
> > > > > > > > > > > >
> > > > > > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > > > > > HW provides two functions:
> > > > > > > > > > > >
> > > > > > > > > > > > 1) 3 axes reports
> > > > > > > > > > > > 2) Disk freefall detection
> > > > > > > > > > > >
> > > > > > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > > > > > >
> > > > > > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > > > > > be more complicated as currently is.
> > > > > > > > > > >
> > > > > > > > > > > Because this apparently does not work for you, does it?
> > > > > > > > > >
> > > > > > > > > > It is working fine. I do not see any problem.
> > > > > > > > > >
> > > > > > > > > > > In general,
> > > > > > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > > > > > are going to have bad time.
> > > > > > > > > >
> > > > > > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > > > > > based. This is problem of ACPI and Dell design.
> > > > > > > > > >
> > > > > > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > > > > > the same, right?
> > > > > > > > > >
> > > > > > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > > > > > provides everything.
> > > > > > > > > >
> > > > > > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > > > > > i2c linux abstractions are different.
> > > > > > > > > >
> > > > > > > > > > > So, instead of having 2 drivers split the
> > > > > > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > > > > > >
> > > > > > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > > > > > .ko module).
> > > > > > > > >
> > > > > > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > > > > > >
> > > > > > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > > > > > >
> > > > > > > > > Any particular reason for that?
> > > > > > > > >
> > > > > > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > > > > > working.
> > > > > > > > >
> > > > > > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > > > > > lis3lv02d handle it.
> > > > > > > > >
> > > > > > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > > > > > >
> > > > > > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > > > > > i2c_client with board_info->irq = -1.
> > > > > > > > >
> > > > > > > > > Pick whichever you prefer.
> > > > > > > > >
> > > > > > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > > > > > don't appear to be tablets that could use one...
> > > > > > > >
> > > > > > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > > > > > not work... I thought that discussion is about different mechanism how
> > > > > > > > to implement bus registration notification to smo8800 driver (or
> > > > > > > > different solution to not have registration in i801).
> > > > > > > >
> > > > > > >
> > > > > > > Just because I am not sure I got everything right, could you confirm
> > > > > > > that:
> > > > > > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > > > > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > > > > > alert)
> > > > > >
> > > > > > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > > > > > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > > > > > i2c.
> > > > > >
> > > > > > > - this series adds an extra lis3lv02d on some machines and you have
> > > > > > > problem fighting for the irq (but this is not upstream yet).
> > > > > >
> > > > > > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > > > > > working because of 4d5538f5882a.
> > > > > >
> > > > > > > The extra lis3lv02d node is added from dell-smo8800
> > > > > >
> > > > > > No, dell-smo8800 does not add new node in this patch.
> > > > > >
> > > > > > > If the first point is not correct (by default, dell-smo8800 will not be
> > > > > > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > > > > > the interactions between those 2 drivers.
> > > > > >
> > > > > > No, there is no interactions between these two drivers (dell-smo8800 and
> > > > > > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > > > > > /dev/freefall device based on IRQ (and nothing more).
> > > > > >
> > > > > > And lis3lv02d in *current* configuration in this patch exports only
> > > > > > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > > > > > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > > > > > number which is not freefall report, therefore lis3lv02d does not work).
> > > > > >
> > > > > > To make it clear, ST Accelerometer provides two operations:
> > > > > > * report free fall
> > > > > > * report 3 axes
> > > > > >
> > > > > > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > > > > > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> > > > > >
> > > > > > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > > > > > IRQ number for it -- but this is not case in our Dell configuration. But
> > > > > > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > > > > > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > > > > > configuration (by this patch) there should be no IRQ number.
> > > > > >
> > > > > > It is clear now?
> > > > >
> > > > > I think I am starting to understand the problem.
> > > > >
> > > > > Currently (upstream tree), 4d5538f5882a doesn't break anything.
> > > >
> > > > I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
> > > > (missing = no freefall) and there could be already hardware/boards which
> > > > register lis3lv02d i2c device without IRQ number. And definitions could
> > > > be also in device tree and so outside of kernel sources...
> > > >
> > > > So there can be potentially break. But at least not case of Dell.
> > > >
> > > > > On the
> > > > > mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> > > > > /dev/freefall. lis3lv02d is not loaded so everything just works.
> > > >
> > > > Yes.
> > > >
> > > > > The problem comes from this patch which doesn't set the irq in
> > > > > i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> > > > > Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> > > > > in i2c_board_info in your patch and only forward it to
> > > > > lis3lv02d_init_device() only if it is positive (valid).
> > > >
> > > > Now I understood that Dmitri means. For this Dell platforms it is OK,
> > > > but we have a problem for device tree platforms. Normally in device tree
> > > > if device does not support something you just do not specify it. But
> > > > with this approach you need to explicitly specify IRQ to -1 in device
> > > > tree. And I think this is really not a clean solution.
> > > >
> >
> > Here I was talking about other platforms/devices (not this Dell one).
> >
> > > No. DT platforms won't have an issue: they don't change anything, and
> > > there will be a new /dev/freefall misc device for the platforms that
> >
> > And this is wrong! There should not be any /dev/freefall device
> > connected with signal host notify. /dev/freefall is for hardware which
> > supports free fall hdd detection.
On the principle, I agree. But let's be realistic: this device will be
created but no events will be generated from it. It's a capability for
the chip to provide freefall, so I don't see why it's such an issue to
have one created which says nothing. (talking about non Dell platforms
here too)
> >
> > > don't have the irq set *and* if the device is on a Host Notify capable
> > > adapter, currently only i2c-i801.
> >
> > I understood, but in future more bus drivers could support host notify.
>
> This is really fragile. lis3lv02d will empty IRQ (0) will work on some
> i2c buses and on some not. I would really expect that i2c driver
> (lis3lv02d) will work in same way with any i2c bus driver. And not that
> on i801 will acts differently as on e.g. omap3 i2c bus.
I really don't follow you here. On a bus with no Host Notify, the IRQ
will be 0 and it will work in the same way. On a bus with Host Notify,
the IRQ should be set to something negative in the i2c_board_info to be
sure to not have an Host Notify irq assigned. In both case the
lis3lv02d_i2c driver will just do:
if (client->irq > 0)
lis3_dev.irq = client->irq;
So there is no bus adapter specifics in the driver.
>
> > This is basically incorrect if we use one property for two different
> > things (host notify and hdd free fall).
Host Notify is a way for a I2C device to report an interrupt without
having a dedicated line assigned (and so an IRQ). So the chip could use
Host Notify to report hdd free fall if it supports the feature.
> >
> > For me it looks like that we should separate these two things into two
> > IRQ properties. It is really wrong design if one property is used for
> > two different things.
I won't say the design is wrong because Host Notify really is just an
IRQ. Where the issue lies now is that lis3lv02d makes the assumption
that an irq attached to an i2c_client means that it will report
freefall. It was correct before, but now it's not true anymore.
So maybe this series should also add a way to provide the source of
the IRQ (Host Notify or ACPI or DT). Then, lis3lv02d could ignore or
not the incoming IRQ.
Cheers,
Benjamin
> >
> > > But given that they are DT and not
> > > ACPI, this won't conflict with dell-smo8800, so there won't be any
> > > errors, just a dangling unused device node.
> >
> > Yes, for upcoming Dell in this patch (with IRQ -1) it is not a problem.
> >
> > > This approach is IMO the best if you want to have this in the kernel.
> > >
> > > Cheers,
> > > Benjamin
> >
>
> --
> Pali Rohár
> pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Pali Rohár <pali.rohar@gmail.com> |
|---|---|
| Date | 2017-01-04 17:10 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVWiu-6Xe-33@gated-at.bofh.it> |
| In reply to | #1550757 |
On Wednesday 04 January 2017 14:02:52 Benjamin Tissoires wrote:
> On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > On Wednesday 04 January 2017 12:22:23 Pali Rohár wrote:
> > > On Wednesday 04 January 2017 11:32:33 Benjamin Tissoires wrote:
> > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > On Wednesday 04 January 2017 11:13:06 Benjamin Tissoires wrote:
> > > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > > On Wednesday 04 January 2017 10:05:22 Benjamin Tissoires wrote:
> > > > > > > > On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> > > > > > > > > On Tuesday 03 January 2017 12:59:37 Dmitry Torokhov wrote:
> > > > > > > > > > On Tue, Jan 03, 2017 at 09:39:13PM +0100, Pali Rohár wrote:
> > > > > > > > > > > On Tuesday 03 January 2017 21:24:18 Dmitry Torokhov wrote:
> > > > > > > > > > > > On Tue, Jan 03, 2017 at 09:05:51PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > > On Tuesday 03 January 2017 20:48:12 Dmitry Torokhov wrote:
> > > > > > > > > > > > > > On Tue, Jan 03, 2017 at 07:50:17PM +0100, Pali Rohár wrote:
> > > > > > > > > > > > > > > On Tuesday 03 January 2017 19:38:43 Dmitry Torokhov wrote:
> > > > > > > > > > > > > > > > On Tue, Jan 03, 2017 at 10:06:41AM +0100, Benjamin Tissoires
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > On Dec 29 2016 or thereabouts, Pali Rohár wrote:
> > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 22:09:32 Michał Kępień wrote:
> > > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 14:47:19 Michał Kępień
> > > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > > On Thursday 29 December 2016 09:29:36 Michał
> > > > > > > > > > > > > > > > > > > > > > Kępień
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > > > > > > > Dell platform team told us that some (DMI
> > > > > > > > > > > > > > > > > > > > > > > > whitelisted) Dell Latitude machines have ST
> > > > > > > > > > > > > > > > > > > > > > > > microelectronics accelerometer at i2c address
> > > > > > > > > > > > > > > > > > > > > > > > 0x29. That i2c address is not specified in
> > > > > > > > > > > > > > > > > > > > > > > > DMI or ACPI, so runtime detection without
> > > > > > > > > > > > > > > > > > > > > > > > whitelist which is below is not possible.
> > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > Presence of that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > > > > accelerometer is verified by existence of
> > > > > > > > > > > > > > > > > > > > > > > > SMO88xx ACPI device which represent that
> > > > > > > > > > > > > > > > > > > > > > > > accelerometer. Unfortunately without i2c
> > > > > > > > > > > > > > > > > > > > > > > > address.
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > This part of the commit message sounded a bit
> > > > > > > > > > > > > > > > > > > > > > > confusing to me at first because there is
> > > > > > > > > > > > > > > > > > > > > > > already an ACPI driver which handles SMO88xx
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > devices (dell-smo8800). My understanding is
> > > > > > > > > > > > > > > > > > > > > > > that:
> > > > > > > > > > > > > > > > > > > > > > > * the purpose of this patch is to expose a
> > > > > > > > > > > > > > > > > > > > > > > richer interface (as
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > provided by lis3lv02d) to these devices on
> > > > > > > > > > > > > > > > > > > > > > > some machines,
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > * on whitelisted machines, dell-smo8800 and
> > > > > > > > > > > > > > > > > > > > > > > lis3lv02d can work
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > simultaneously (even though dell-smo8800
> > > > > > > > > > > > > > > > > > > > > > > effectively duplicates the work that
> > > > > > > > > > > > > > > > > > > > > > > lis3lv02d does).
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > No. dell-smo8800 reads from ACPI irq number and
> > > > > > > > > > > > > > > > > > > > > > exports /dev/freefall device which notify
> > > > > > > > > > > > > > > > > > > > > > userspace about falls. lis3lv02d is i2c driver
> > > > > > > > > > > > > > > > > > > > > > which exports axes of accelerometer. Additionaly
> > > > > > > > > > > > > > > > > > > > > > lis3lv02d can export also /dev/freefall if
> > > > > > > > > > > > > > > > > > > > > > registerer of i2c device provides irq number --
> > > > > > > > > > > > > > > > > > > > > > which is not case of this patch.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > So both drivers are doing different things and
> > > > > > > > > > > > > > > > > > > > > > both are useful.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > IIRC both dell-smo8800 and lis3lv02d represent
> > > > > > > > > > > > > > > > > > > > > > one HW device (that ST microelectronics
> > > > > > > > > > > > > > > > > > > > > > accelerometer) but due to complicated HW
> > > > > > > > > > > > > > > > > > > > > > abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > Yes, in ideal world irq number should be passed
> > > > > > > > > > > > > > > > > > > > > > to lis3lv02d driver and that would export whole
> > > > > > > > > > > > > > > > > > > > > > device (with /dev/freefall too), but due to HW
> > > > > > > > > > > > > > > > > > > > > > abstraction it is too much complicated...
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > Why? AFAICT, all that is required to pass that IRQ
> > > > > > > > > > > > > > > > > > > > > number all the way down to lis3lv02d is to set the
> > > > > > > > > > > > > > > > > > > > > irq field of the struct i2c_board_info you are
> > > > > > > > > > > > > > > > > > > > > passing to i2c_new_device(). And you can extract
> > > > > > > > > > > > > > > > > > > > > that IRQ number e.g. in
> > > > > > > > > > > > > > > > > > > > > check_acpi_smo88xx_device(). However, you would
> > > > > > > > > > > > > > > > > > > > > then need to make sure dell-smo8800 does not
> > > > > > > > > > > > > > > > > > > > > attempt to request the same IRQ on whitelisted
> > > > > > > > > > > > > > > > > > > > > machines. This got me thinking about a way to
> > > > > > > > > > > > > > > > > > > > > somehow incorporate your changes into dell-smo8800
> > > > > > > > > > > > > > > > > > > > > using Wolfram's bus_notifier suggestion, but I do
> > > > > > > > > > > > > > > > > > > > > not have a working solution for now. What is
> > > > > > > > > > > > > > > > > > > > > tempting about this approach is that you would not
> > > > > > > > > > > > > > > > > > > > > have to scan the ACPI namespace in search of
> > > > > > > > > > > > > > > > > > > > > SMO88xx devices, because smo8800_add() is
> > > > > > > > > > > > > > > > > > > > > automatically called for them. However, I fear that
> > > > > > > > > > > > > > > > > > > > > the resulting solution may be more complicated than
> > > > > > > > > > > > > > > > > > > > > the one you submitted.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Then we need to deal with lot of problems. Order of
> > > > > > > > > > > > > > > > > > > > loading .ko modules is undefined. Binding devices to
> > > > > > > > > > > > > > > > > > > > drivers registered by .ko module is also in "random"
> > > > > > > > > > > > > > > > > > > > order. At any time any of those .ko module can be
> > > > > > > > > > > > > > > > > > > > unloaded or at least device unbind (via sysfs) from
> > > > > > > > > > > > > > > > > > > > driver... And there can be some pathological
> > > > > > > > > > > > > > > > > > > > situation (thanks to adding ACPI layer as Andy
> > > > > > > > > > > > > > > > > > > > pointed) that there will be more SMO88xx devices in
> > > > > > > > > > > > > > > > > > > > ACPI. Plus you can compile kernel with and without
> > > > > > > > > > > > > > > > > > > > those modules and also you can blacklist loading
> > > > > > > > > > > > > > > > > > > > them (so compile time check is not enough). And
> > > > > > > > > > > > > > > > > > > > still some correct message notifier must be used.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > I think such solution is much much more complicated,
> > > > > > > > > > > > > > > > > > > > there are lot of combinations of kernel configuration
> > > > > > > > > > > > > > > > > > > > and available dell devices...
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > I tried a few more things, but ultimately failed to
> > > > > > > > > > > > > > > > > > > find a nice way to implement this.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Another issue popped up, though. Linus' master branch
> > > > > > > > > > > > > > > > > > > contains a recent commit by Benjamin Tissoires (CC'ed),
> > > > > > > > > > > > > > > > > > > 4d5538f5882a ("i2c: use an IRQ to report Host Notify
> > > > > > > > > > > > > > > > > > > events, not alert") which breaks your patch. The
> > > > > > > > > > > > > > > > > > > reason for that is that lis3lv02d relies on the i2c
> > > > > > > > > > > > > > > > > > > client's IRQ being 0 to detect that it should not
> > > > > > > > > > > > > > > > > > > create /dev/freefall.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Benjamin's patch causes the Host Notify IRQ to be
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > assigned to the i2c client your patch creates, thus
> > > > > > > > > > > > > > > > > > > causing lis3lv02d to create /dev/freefall, which in
> > > > > > > > > > > > > > > > > > > turn conflicts with dell-smo8800 which is trying to
> > > > > > > > > > > > > > > > > > > create /dev/freefall itself.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > So 4d5538f5882a is breaking lis3lv02d driver...
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Apologies for that.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I could easily fix this by adding a kernel API to know
> > > > > > > > > > > > > > > > > whether the provided irq is from Host Notify or if it was
> > > > > > > > > > > > > > > > > coming from an actual declaration. However, I have no idea
> > > > > > > > > > > > > > > > > how many other drivers would require this (hopefully only
> > > > > > > > > > > > > > > > > this one).
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > One other solution would be to reserve the Host Notify IRQ
> > > > > > > > > > > > > > > > > and let the actual drivers that need it to set it, but
> > > > > > > > > > > > > > > > > this was not the best solution according to Dmitri. On my
> > > > > > > > > > > > > > > > > side, I am not entirely against this given that it's a
> > > > > > > > > > > > > > > > > chip feature, so the driver should be able to know that
> > > > > > > > > > > > > > > > > it's available.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Dmitri, Wolfram, Jean, any preferences?
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > I read this:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > "IIRC both dell-smo8800 and lis3lv02d represent one HW device
> > > > > > > > > > > > > > > > (that ST microelectronics accelerometer) but due to
> > > > > > > > > > > > > > > > complicated HW abstraction and layers on Dell laptops it is
> > > > > > > > > > > > > > > > handled by two drivers, one ACPI and one i2c."
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > and that is the core of the issue. You have 2 drivers
> > > > > > > > > > > > > > > > fighting over the same device. Fix this and it will all
> > > > > > > > > > > > > > > > work.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > With my current implementation (which I sent in this patch),
> > > > > > > > > > > > > > > they are not fighting.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > dell-smo8800 exports /dev/freefall (and nothing more) and
> > > > > > > > > > > > > > > lis3lv02d only accelerometer device as lis3lv02d driver does
> > > > > > > > > > > > > > > not get IRQ number in platform data.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > As far as I can see hp_accel instantiates lis3lv02d and
> > > > > > > > > > > > > > > > accesses it via ACPI methods, can the same be done for Dell?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > No, Dell does not have any ACPI methods. And as I wrote in ACPI
> > > > > > > > > > > > > > > or DMI is even not i2c address of device, so it needs to be
> > > > > > > > > > > > > > > specified in code itself.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Really there is no other way... :-(
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Sure there is:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > 1. dell-smo8800 instantiates I2C device as "dell-smo8800-accel".
> > > > > > > > > > > > > > 2. dell-smo8800 provides read/write functions for lis3lv02d that
> > > > > > > > > > > > > > simply forward requests to dell-smo8800-accel i2c client.
> > > > > > > > > > > > > > 3. dell-smo8800 instantiates lis3lv02d instance like hp_accel
> > > > > > > > > > > > > > does.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Sorry, but I do not understand how you mean it... Why to provides
> > > > > > > > > > > > > new read/write i2c functions which are already implemented by
> > > > > > > > > > > > > i2c-i801 bus and lis3lv02d i2c driver?
> > > > > > > > > > > >
> > > > > > > > > > > > Because that would allow you to avoid clashes with i2c creating
> > > > > > > > > > > > interrupt mapping for client residing on host-notify-capable
> > > > > > > > > > > > controller.
> > > > > > > > > > > >
> > > > > > > > > > > > > > Alternatively, can lis3lv02d be tasked to create /dev/freefall?
> > > > > > > > > > > > >
> > > > > > > > > > > > > If i2c_board_info contains IRQ then lis3lv02d create /dev/freefall
> > > > > > > > > > > > > device.
> > > > > > > > > > > > >
> > > > > > > > > > > > > But... what is problem with current implementation? Accelerometer
> > > > > > > > > > > > > HW provides two functions:
> > > > > > > > > > > > >
> > > > > > > > > > > > > 1) 3 axes reports
> > > > > > > > > > > > > 2) Disk freefall detection
> > > > > > > > > > > > >
> > > > > > > > > > > > > And 1) is handled by i2c driver lis3lv02d and 2) is by
> > > > > > > > > > > > > dell-smo8800. Both functions are independent here.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I think you just trying to complicate this situation even more to
> > > > > > > > > > > > > be more complicated as currently is.
> > > > > > > > > > > >
> > > > > > > > > > > > Because this apparently does not work for you, does it?
> > > > > > > > > > >
> > > > > > > > > > > It is working fine. I do not see any problem.
> > > > > > > > > > >
> > > > > > > > > > > > In general,
> > > > > > > > > > > > if you want the same hardware be handled by 2 different drivers you
> > > > > > > > > > > > are going to have bad time.
> > > > > > > > > > >
> > > > > > > > > > > Yes, but in this case half of device is ACPI based and other half i2c
> > > > > > > > > > > based. This is problem of ACPI and Dell design.
> > > > > > > > > > >
> > > > > > > > > > > > It seems to be that /dev/freefall in dell-smo8800 and lis3lv02d are
> > > > > > > > > > > > the same, right?
> > > > > > > > > > >
> > > > > > > > > > > Yes. I understand that clean solution is to have one driver which
> > > > > > > > > > > provides everything.
> > > > > > > > > > >
> > > > > > > > > > > But because half of data are ACPI and half i2c, you still needs to
> > > > > > > > > > > create two drivers (one ACPI and one i2c). You can put both drivers into
> > > > > > > > > > > one .ko module, but still these will be two drivers due to how ACPI and
> > > > > > > > > > > i2c linux abstractions are different.
> > > > > > > > > > >
> > > > > > > > > > > > So, instead of having 2 drivers split the
> > > > > > > > > > > > functionality, can you forego registering smo8800 ACPI driver on
> > > > > > > > > > > > your whitelisted boxes and instead instantiate full i2c client
> > > > > > > > > > > > device with properly assigned both address and IRQ and let lis3lv02d
> > > > > > > > > > > > handle it (providing both accelerometer data and /dev/freefall)?
> > > > > > > > > > >
> > > > > > > > > > > With Michał we already discussed about it, see emails. Basically you can
> > > > > > > > > > > enable/disable kernel modules at compile time or blacklist at runtime
> > > > > > > > > > > (or even chose what will be compiled into vmlinux and what as external
> > > > > > > > > > > .ko module).
> > > > > > > > > >
> > > > > > > > > > This can be solved with a bit of Kconfig/IS_ENABLED() code.
> > > > > > > > > >
> > > > > > > > > > > Some distributions blacklist i2c-i801.ko module... And
> > > > > > > > > >
> > > > > > > > > > Any particular reason for that?
> > > > > > > > > >
> > > > > > > > > > > there can be also problem with initialization of i2c-i801 driver (fix is
> > > > > > > > > > > in commit a7ae81952cda, but does not have to work at every time!). So
> > > > > > > > > > > that move on whitelisted machines can potentially cause disappearance of
> > > > > > > > > > > /dev/freefall and users will not have hdd protection which is currently
> > > > > > > > > > > working.
> > > > > > > > > >
> > > > > > > > > > Well, I gave you 2 possible solutions (roll your own i2c read/write,
> > > > > > > > > > forward them to i2c client) or have faith in your implementation and let
> > > > > > > > > > lis3lv02d handle it.
> > > > > > > > > >
> > > > > > > > > > The 3rd one is to possibly add a flag to disable host notify to IRQ
> > > > > > > > > > mapping for given client (if Wolfram/Jean OK with it).
> > > > > > > > > >
> > > > > > > > > > Oh, the 4th one: change the irq in lis3lv02d.h to be "int" and change
> > > > > > > > > > the check in lis3lv02d.c to be "lis->irq <= 0" and instantiate your
> > > > > > > > > > i2c_client with board_info->irq = -1.
> > > > > > > > > >
> > > > > > > > > > Pick whichever you prefer.
> > > > > > > > > >
> > > > > > > > > > By the way, what do you need accelerometer for on these devices? They
> > > > > > > > > > don't appear to be tablets that could use one...
> > > > > > > > >
> > > > > > > > > Ah, you are talking about problem that after 4d5538f5882a lis3lv02d will
> > > > > > > > > not work... I thought that discussion is about different mechanism how
> > > > > > > > > to implement bus registration notification to smo8800 driver (or
> > > > > > > > > different solution to not have registration in i801).
> > > > > > > > >
> > > > > > > >
> > > > > > > > Just because I am not sure I got everything right, could you confirm
> > > > > > > > that:
> > > > > > > > - in the current upstream tree, the dell-smo8800 driver is now broken
> > > > > > > > after 4d5538f5882a (i2c: use an IRQ to report Host Notify events, not
> > > > > > > > alert)
> > > > > > >
> > > > > > > No, dell-smo8800 it is working fine. It is fully independent from i2c
> > > > > > > and lis3lv02d. It is pure ACPI driver which does not share anything with
> > > > > > > i2c.
> > > > > > >
> > > > > > > > - this series adds an extra lis3lv02d on some machines and you have
> > > > > > > > problem fighting for the irq (but this is not upstream yet).
> > > > > > >
> > > > > > > Yes, this series (not merged yet) adds extra lis3lv02d device but is not
> > > > > > > working because of 4d5538f5882a.
> > > > > > >
> > > > > > > > The extra lis3lv02d node is added from dell-smo8800
> > > > > > >
> > > > > > > No, dell-smo8800 does not add new node in this patch.
> > > > > > >
> > > > > > > > If the first point is not correct (by default, dell-smo8800 will not be
> > > > > > > > loaded at the same time than lis3lv02d), then it's a design issue with
> > > > > > > > the interactions between those 2 drivers.
> > > > > > >
> > > > > > > No, there is no interactions between these two drivers (dell-smo8800 and
> > > > > > > lis3lv02d). dell-smo8800 is pure ACPI driver and exports just
> > > > > > > /dev/freefall device based on IRQ (and nothing more).
> > > > > > >
> > > > > > > And lis3lv02d in *current* configuration in this patch exports only
> > > > > > > accelerometer input device, not /dev/freefall. It does not use IRQ.
> > > > > > > (Just there is problem with 4d5538f5882a which tells lis3lv02d IRQ
> > > > > > > number which is not freefall report, therefore lis3lv02d does not work).
> > > > > > >
> > > > > > > To make it clear, ST Accelerometer provides two operations:
> > > > > > > * report free fall
> > > > > > > * report 3 axes
> > > > > > >
> > > > > > > Free fall is reported by IRQ, state of 3 axes via i2c bus. Free fall IRQ
> > > > > > > is handled by dell-smo8800, state of 3 axes via i2c lis3lv02d driver.
> > > > > > >
> > > > > > > lis3lv02d can handle also free fall IRQ is platform i2c data provides
> > > > > > > IRQ number for it -- but this is not case in our Dell configuration. But
> > > > > > > commit 4d5538f5882a inject some IRQ number to lis3lv02d driver which is
> > > > > > > not free fall detection and so is breaking lis3lv02 driver. In our Dell
> > > > > > > configuration (by this patch) there should be no IRQ number.
> > > > > > >
> > > > > > > It is clear now?
> > > > > >
> > > > > > I think I am starting to understand the problem.
> > > > > >
> > > > > > Currently (upstream tree), 4d5538f5882a doesn't break anything.
> > > > >
> > > > > I cannot prove it... lis3lv02d i2c driver itself uses this IRQ logic
> > > > > (missing = no freefall) and there could be already hardware/boards which
> > > > > register lis3lv02d i2c device without IRQ number. And definitions could
> > > > > be also in device tree and so outside of kernel sources...
> > > > >
> > > > > So there can be potentially break. But at least not case of Dell.
> > > > >
> > > > > > On the
> > > > > > mentioned Dell platforms, the dell-smo8800 gets loaded and provides
> > > > > > /dev/freefall. lis3lv02d is not loaded so everything just works.
> > > > >
> > > > > Yes.
> > > > >
> > > > > > The problem comes from this patch which doesn't set the irq in
> > > > > > i2c_board_info and so i2c_core sets the IRQ to Host Notify. I think
> > > > > > Dmitri already gave you the solution: set the irq to -1 (or -ENOENT)
> > > > > > in i2c_board_info in your patch and only forward it to
> > > > > > lis3lv02d_init_device() only if it is positive (valid).
> > > > >
> > > > > Now I understood that Dmitri means. For this Dell platforms it is OK,
> > > > > but we have a problem for device tree platforms. Normally in device tree
> > > > > if device does not support something you just do not specify it. But
> > > > > with this approach you need to explicitly specify IRQ to -1 in device
> > > > > tree. And I think this is really not a clean solution.
> > > > >
> > >
> > > Here I was talking about other platforms/devices (not this Dell one).
> > >
> > > > No. DT platforms won't have an issue: they don't change anything, and
> > > > there will be a new /dev/freefall misc device for the platforms that
> > >
> > > And this is wrong! There should not be any /dev/freefall device
> > > connected with signal host notify. /dev/freefall is for hardware which
> > > supports free fall hdd detection.
>
> On the principle, I agree. But let's be realistic: this device will be
> created but no events will be generated from it.
And I think this is a problem. This provides false information to kernel
and also to userspace applications that there is working free fall
sensor (even there is not).
> It's a capability for the chip to provide freefall,
That it is not truth. Not every chip has it. Platform data are there to
provides this information for driver, if HW has freefall capability or
not.
> so I don't see why it's such an issue to
> have one created which says nothing. (talking about non Dell platforms
> here too)
>
> > >
> > > > don't have the irq set *and* if the device is on a Host Notify capable
> > > > adapter, currently only i2c-i801.
> > >
> > > I understood, but in future more bus drivers could support host notify.
> >
> > This is really fragile. lis3lv02d will empty IRQ (0) will work on some
> > i2c buses and on some not. I would really expect that i2c driver
> > (lis3lv02d) will work in same way with any i2c bus driver. And not that
> > on i801 will acts differently as on e.g. omap3 i2c bus.
>
> I really don't follow you here. On a bus with no Host Notify, the IRQ
> will be 0 and it will work in the same way.
That it OK.
> On a bus with Host Notify,
> the IRQ should be set to something negative in the i2c_board_info
Not only in i2c_board_info but also in DTS. Which means every one DTS
needs to be updates -- also those outside of linux kernel. Which is for
me wrong.
> to be
> sure to not have an Host Notify irq assigned. In both case the
> lis3lv02d_i2c driver will just do:
> if (client->irq > 0)
> lis3_dev.irq = client->irq;
>
> So there is no bus adapter specifics in the driver.
>
> >
> > > This is basically incorrect if we use one property for two different
> > > things (host notify and hdd free fall).
>
> Host Notify is a way for a I2C device to report an interrupt without
> having a dedicated line assigned (and so an IRQ).
Yes. But lis3lv02d i2c devices which I have uses dedicated IRQ. They
does not work in way like you describe.
> So the chip could use
> Host Notify to report hdd free fall if it supports the feature.
Old existing HW could not. As those were not designed for such purpose.
Yes, new HW can be designed in this way, but linux kernel should not
drop (or modify) correct support for old HW devices just because there
is new HW design.
> > >
> > > For me it looks like that we should separate these two things into two
> > > IRQ properties. It is really wrong design if one property is used for
> > > two different things.
>
> I won't say the design is wrong because Host Notify really is just an
> IRQ.
Yes it is IRQ, but different. And lis3lv02d does not issue host notify
IRQ, so it should not be assigned to lis3lv02d.
> Where the issue lies now is that lis3lv02d makes the assumption
> that an irq attached to an i2c_client means that it will report
> freefall.
Yes.
> It was correct before, but now it's not true anymore.
Agree.
> So maybe this series should also add a way to provide the source of
> the IRQ (Host Notify or ACPI or DT). Then, lis3lv02d could ignore or
> not the incoming IRQ.
Yes, this is an option how to fix this problem.
I would rather introduce new IRQ property in both DTS and lis3lv02d
platform data (e.g. irq-freefall) which will unambiguously identify
freefall IRQ.
But I do not think it should be part of my Dell patch. It is
independent fix for lis3lv02d driver for bug which was introduced by
commit 4d5538f5882a.
>
> Cheers,
> Benjamin
>
> > >
> > > > But given that they are DT and not
> > > > ACPI, this won't conflict with dell-smo8800, so there won't be any
> > > > errors, just a dangling unused device node.
> > >
> > > Yes, for upcoming Dell in this patch (with IRQ -1) it is not a problem.
> > >
> > > > This approach is IMO the best if you want to have this in the kernel.
> > > >
> > > > Cheers,
> > > > Benjamin
> > >
> >
> > --
> > Pali Rohár
> > pali.rohar@gmail.com
--
Pali Rohár
pali.rohar@gmail.com
[toc] | [prev] | [next] | [standalone]
| From | Benjamin Tissoires <benjamin.tissoires@redhat.com> |
|---|---|
| Date | 2017-01-04 18:40 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVXHB-7LF-73@gated-at.bofh.it> |
| In reply to | #1550956 |
On Jan 04 2017 or thereabouts, Pali Rohár wrote:
> On Wednesday 04 January 2017 14:02:52 Benjamin Tissoires wrote:
> > > > > No. DT platforms won't have an issue: they don't change anything, and
> > > > > there will be a new /dev/freefall misc device for the platforms that
> > > >
> > > > And this is wrong! There should not be any /dev/freefall device
> > > > connected with signal host notify. /dev/freefall is for hardware which
> > > > supports free fall hdd detection.
> >
> > On the principle, I agree. But let's be realistic: this device will be
> > created but no events will be generated from it.
>
> And I think this is a problem. This provides false information to kernel
> and also to userspace applications that there is working free fall
> sensor (even there is not).
>
> > It's a capability for the chip to provide freefall,
>
> That it is not truth. Not every chip has it. Platform data are there to
> provides this information for driver, if HW has freefall capability or
> not.
>
> > so I don't see why it's such an issue to
> > have one created which says nothing. (talking about non Dell platforms
> > here too)
> >
> > > >
> > > > > don't have the irq set *and* if the device is on a Host Notify capable
> > > > > adapter, currently only i2c-i801.
> > > >
> > > > I understood, but in future more bus drivers could support host notify.
> > >
> > > This is really fragile. lis3lv02d will empty IRQ (0) will work on some
> > > i2c buses and on some not. I would really expect that i2c driver
> > > (lis3lv02d) will work in same way with any i2c bus driver. And not that
> > > on i801 will acts differently as on e.g. omap3 i2c bus.
> >
> > I really don't follow you here. On a bus with no Host Notify, the IRQ
> > will be 0 and it will work in the same way.
>
> That it OK.
>
> > On a bus with Host Notify,
> > the IRQ should be set to something negative in the i2c_board_info
>
> Not only in i2c_board_info but also in DTS. Which means every one DTS
> needs to be updates -- also those outside of linux kernel. Which is for
> me wrong.
>
> > to be
> > sure to not have an Host Notify irq assigned. In both case the
> > lis3lv02d_i2c driver will just do:
> > if (client->irq > 0)
> > lis3_dev.irq = client->irq;
> >
> > So there is no bus adapter specifics in the driver.
> >
> > >
> > > > This is basically incorrect if we use one property for two different
> > > > things (host notify and hdd free fall).
> >
> > Host Notify is a way for a I2C device to report an interrupt without
> > having a dedicated line assigned (and so an IRQ).
>
> Yes. But lis3lv02d i2c devices which I have uses dedicated IRQ. They
> does not work in way like you describe.
>
> > So the chip could use
> > Host Notify to report hdd free fall if it supports the feature.
>
> Old existing HW could not. As those were not designed for such purpose.
>
> Yes, new HW can be designed in this way, but linux kernel should not
> drop (or modify) correct support for old HW devices just because there
> is new HW design.
I never said we should drop support of old hardware. I was just
explaining what is Host Notify and saying that it is not incompatible
with lis3lv02d.
>
> > > >
> > > > For me it looks like that we should separate these two things into two
> > > > IRQ properties. It is really wrong design if one property is used for
> > > > two different things.
> >
> > I won't say the design is wrong because Host Notify really is just an
> > IRQ.
>
> Yes it is IRQ, but different. And lis3lv02d does not issue host notify
> IRQ, so it should not be assigned to lis3lv02d.
Sigh.
>
> > Where the issue lies now is that lis3lv02d makes the assumption
> > that an irq attached to an i2c_client means that it will report
> > freefall.
>
> Yes.
>
> > It was correct before, but now it's not true anymore.
>
> Agree.
>
> > So maybe this series should also add a way to provide the source of
> > the IRQ (Host Notify or ACPI or DT). Then, lis3lv02d could ignore or
> > not the incoming IRQ.
>
> Yes, this is an option how to fix this problem.
How about:
---
From daa7571bbf337704332c0cfeec9b8fd5aeae596f Mon Sep 17 00:00:00 2001
From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Date: Wed, 4 Jan 2017 18:26:54 +0100
Subject: [PATCH] I2C: add the source of the IRQ in struct i2c_client
With commit 4d5538f5882a ("i2c: use an IRQ to report Host Notify events,
not alert"), the IRQ provided in struct i2c_client might be assigned while
it has not been explicitly declared by either the platform information
or OF or ACPI.
Some drivers (lis3lv02d) rely on the fact that the IRQ gets assigned or
not to trigger a different behavior (exposing /dev/freefall in this case).
Provide a way for others to know who set the IRQ and so they can behave
accordingly.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
---
drivers/i2c/i2c-core.c | 7 +++++++
include/linux/i2c.h | 11 +++++++++++
2 files changed, 18 insertions(+)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index cf9e396..226c75d 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -935,8 +935,12 @@ static int i2c_device_probe(struct device *dev)
irq = of_irq_get_byname(dev->of_node, "irq");
if (irq == -EINVAL || irq == -ENODATA)
irq = of_irq_get(dev->of_node, 0);
+ if (irq > 0)
+ client->irq_source = I2C_IRQ_SOURCE_OF;
} else if (ACPI_COMPANION(dev)) {
irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
+ if (irq > 0)
+ client->irq_source = I2C_IRQ_SOURCE_ACPI;
}
if (irq == -EPROBE_DEFER)
return irq;
@@ -947,6 +951,8 @@ static int i2c_device_probe(struct device *dev)
if (irq < 0) {
dev_dbg(dev, "Using Host Notify IRQ\n");
irq = i2c_smbus_host_notify_to_irq(client);
+ if (irq > 0)
+ client->irq_source = I2C_IRQ_SOURCE_HOST_NOTIFY;
}
if (irq < 0)
irq = 0;
@@ -1317,6 +1323,7 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
client->flags = info->flags;
client->addr = info->addr;
client->irq = info->irq;
+ client->irq_source = I2C_IRQ_SOURCE_PLATFORM;
strlcpy(client->name, info->type, sizeof(client->name));
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b2109c5..7d0368d 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -213,6 +213,13 @@ struct i2c_driver {
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
+enum i2c_irq_source {
+ I2C_IRQ_SOURCE_PLATFORM,
+ I2C_IRQ_SOURCE_OF,
+ I2C_IRQ_SOURCE_ACPI,
+ I2C_IRQ_SOURCE_HOST_NOTIFY,
+};
+
/**
* struct i2c_client - represent an I2C slave device
* @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
@@ -227,6 +234,9 @@ struct i2c_driver {
* userspace_devices list
* @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
* calls it to pass on slave events to the slave driver.
+ * @irq_source: Enum which provides the source of the IRQ. Useful to know
+ * if the IRQ was issued from Host Notify or if it was provided by an other
+ * component.
*
* An i2c_client identifies a single device (i.e. chip) connected to an
* i2c bus. The behaviour exposed to Linux is defined by the driver
@@ -245,6 +255,7 @@ struct i2c_client {
#if IS_ENABLED(CONFIG_I2C_SLAVE)
i2c_slave_cb_t slave_cb; /* callback for slave mode */
#endif
+ enum i2c_irq_source irq_source; /* which component assigned the irq */
};
#define to_i2c_client(d) container_of(d, struct i2c_client, dev)
--
2.9.3
---
Dmitry, Wolfram, Jean, would this be acceptable for you?
>
> I would rather introduce new IRQ property in both DTS and lis3lv02d
> platform data (e.g. irq-freefall) which will unambiguously identify
> freefall IRQ.
Sigh. You asked above to not break existing DT bindings, so I don't
understand why you suddenly want to change every bindings by introducing
a change which breaks backward compatibility.
>
> But I do not think it should be part of my Dell patch. It is
> independent fix for lis3lv02d driver for bug which was introduced by
> commit 4d5538f5882a.
It's not part of the dell patch, but it can be part of the series you
are about to send. Please remember that the current state is that there
is no breakage (only a spurious /dev/freefall which you are not happy
about). The only breakage is with your patch, so it doesn't hurt to have
both sent together so you can control all the requirements at once.
So please incorporate my patch in your series if Wolfram, Jean and Dmitry
agree, and also add the fix in lis3lv02d_i2c to make use of the IRQ source.
Cheers,
Benjamin
>
> >
> > Cheers,
> > Benjamin
> >
> > > >
> > > > > But given that they are DT and not
> > > > > ACPI, this won't conflict with dell-smo8800, so there won't be any
> > > > > errors, just a dangling unused device node.
> > > >
> > > > Yes, for upcoming Dell in this patch (with IRQ -1) it is not a problem.
> > > >
> > > > > This approach is IMO the best if you want to have this in the kernel.
> > > > >
> > > > > Cheers,
> > > > > Benjamin
> > > >
> > >
> > > --
> > > Pali Rohár
> > > pali.rohar@gmail.com
>
> --
> Pali Rohár
> pali.rohar@gmail.com
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| From | Wolfram Sang <wsa@the-dreams.de> |
|---|---|
| Date | 2017-01-04 18:50 +0100 |
| Subject | Re: [PATCH] i2c: i801: Register optional lis3lv02d i2c device on Dell machines |
| Message-ID | <sVXRg-7OT-23@gated-at.bofh.it> |
| In reply to | #1551021 |
> How about:
> ---
> From daa7571bbf337704332c0cfeec9b8fd5aeae596f Mon Sep 17 00:00:00 2001
> From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> Date: Wed, 4 Jan 2017 18:26:54 +0100
> Subject: [PATCH] I2C: add the source of the IRQ in struct i2c_client
>
> With commit 4d5538f5882a ("i2c: use an IRQ to report Host Notify events,
> not alert"), the IRQ provided in struct i2c_client might be assigned while
> it has not been explicitly declared by either the platform information
> or OF or ACPI.
> Some drivers (lis3lv02d) rely on the fact that the IRQ gets assigned or
> not to trigger a different behavior (exposing /dev/freefall in this case).
>
> Provide a way for others to know who set the IRQ and so they can behave
> accordingly.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> ---
> drivers/i2c/i2c-core.c | 7 +++++++
> include/linux/i2c.h | 11 +++++++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index cf9e396..226c75d 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -935,8 +935,12 @@ static int i2c_device_probe(struct device *dev)
> irq = of_irq_get_byname(dev->of_node, "irq");
> if (irq == -EINVAL || irq == -ENODATA)
> irq = of_irq_get(dev->of_node, 0);
> + if (irq > 0)
> + client->irq_source = I2C_IRQ_SOURCE_OF;
> } else if (ACPI_COMPANION(dev)) {
> irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
> + if (irq > 0)
> + client->irq_source = I2C_IRQ_SOURCE_ACPI;
> }
> if (irq == -EPROBE_DEFER)
> return irq;
> @@ -947,6 +951,8 @@ static int i2c_device_probe(struct device *dev)
> if (irq < 0) {
> dev_dbg(dev, "Using Host Notify IRQ\n");
> irq = i2c_smbus_host_notify_to_irq(client);
> + if (irq > 0)
> + client->irq_source = I2C_IRQ_SOURCE_HOST_NOTIFY;
> }
> if (irq < 0)
> irq = 0;
> @@ -1317,6 +1323,7 @@ i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
> client->flags = info->flags;
> client->addr = info->addr;
> client->irq = info->irq;
> + client->irq_source = I2C_IRQ_SOURCE_PLATFORM;
>
> strlcpy(client->name, info->type, sizeof(client->name));
>
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index b2109c5..7d0368d 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -213,6 +213,13 @@ struct i2c_driver {
> };
> #define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
>
> +enum i2c_irq_source {
> + I2C_IRQ_SOURCE_PLATFORM,
> + I2C_IRQ_SOURCE_OF,
> + I2C_IRQ_SOURCE_ACPI,
> + I2C_IRQ_SOURCE_HOST_NOTIFY,
> +};
> +
> /**
> * struct i2c_client - represent an I2C slave device
> * @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
> @@ -227,6 +234,9 @@ struct i2c_driver {
> * userspace_devices list
> * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
> * calls it to pass on slave events to the slave driver.
> + * @irq_source: Enum which provides the source of the IRQ. Useful to know
> + * if the IRQ was issued from Host Notify or if it was provided by an other
> + * component.
I'd think some documentation somewhere makes sense why we need to
distinguish this in some cases?
> *
> * An i2c_client identifies a single device (i.e. chip) connected to an
> * i2c bus. The behaviour exposed to Linux is defined by the driver
> @@ -245,6 +255,7 @@ struct i2c_client {
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> i2c_slave_cb_t slave_cb; /* callback for slave mode */
> #endif
> + enum i2c_irq_source irq_source; /* which component assigned the irq */
> };
> #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
>
> Dmitry, Wolfram, Jean, would this be acceptable for you?
Adding something to i2c_driver is not exactly cheap, but from what I
glimpsed from this thread, this is one of the cleanest solution to this
problem?
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