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Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support

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On Mon, Nov 7, 2016 at 10:22 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> On Thu, Oct 27, 2016 at 05:25:51PM +0200, Greg Kroah-Hartman wrote:
>> On Wed, Oct 26, 2016 at 01:19:02PM +0200, Lukas Wunner wrote:
>> > Hi Rafael,
>> >
>> > sorry for not responding to v5 of your series earlier, just sending
>> > this out now in the hope that it reaches you before your travels.
>> >
>> > On Mon, Oct 10, 2016 at 02:51:04PM +0200, Rafael J. Wysocki wrote:
>> > > - Modify device_links_check_suppliers(), device_links_driver_bound(),
>> > >   device_links_no_driver(), device_links_driver_cleanup(), device_links_busy(),
>> > >   and device_links_unbind_consumers() to walk link lists under device_links_lock
>> > >   (to make the new "driver presence tracking" mechanism work reliably).
>> >
>> > This change might increase boot time if drivers return -EPROBE_DEFER.
>>
>> "might"?  Please verify this before guessing....
>>
>> And don't make this more complex than needed before actually determining
>> a real issue.
>
> As clarified by Rafael at Plumbers, this functional dependencies
> framework assumes your driver / subsystem supports deferred probe,

It isn't particularly clear what you mean by "support" here.

I guess that you mean that it will allow the ->probe callback to be
invoked for multiple times for the same device/driver combination
without issues.  If that's the case, the way the new code uses
-EPROBE_DEFER doesn't interfere with this, because it will not invoke
the ->probe callbacks for consumers at all until their (required)
suppliers are ready.

> if it does not support its not clear what will happen....

I don't see any problems here, but if you see any, please just say
what they are.

> We have no explicit semantics to check if a driver / subsystem
> supports deferred probe.

That's correct, but then do we need it?

Thanks,
Rafael

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Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-27 17:40 +0200
  Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Lukas Wunner <lukas@wunner.de> - 2016-10-28 12:00 +0200
  Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-07 22:30 +0100
    Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-08 07:50 +0100
      Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-08 20:30 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-08 20:50 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-08 22:00 +0100
            Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 07:50 +0100
              Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Andrzej Hajda <a.hajda@samsung.com> - 2016-11-09 10:40 +0100
                Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-09 10:50 +0100
    Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-10 01:50 +0100
      Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 02:10 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-11-10 08:20 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 23:10 +0100
            Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-10 23:50 +0100
              Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2016-11-11 01:10 +0100
        Re: [PATCH v5 2/5] driver core: Functional dependencies tracking support Geert Uytterhoeven <geert@linux-m68k.org> - 2016-11-10 09:50 +0100
          Re: [PATCH v5 2/5] driver core: Functional dependencies tracking  support "Luis R. Rodriguez" <mcgrof@kernel.org> - 2016-11-10 23:20 +0100

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