Re: [RESEND] Lenovo Yoga 900 touchpad issues

From	Mika Westerberg <mika.westerberg@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [RESEND] Lenovo Yoga 900 touchpad issues
Date	2015-12-21 12:40 +0100
Message-ID	<qI6YN-5TQ-9@gated-at.bofh.it> (permalink)
References	(1 earlier) <qGgzg-8nq-13@gated-at.bofh.it> <qGtd8-7St-9@gated-at.bofh.it> <qH4w2-6U7-17@gated-at.bofh.it> <qH5s6-7vm-23@gated-at.bofh.it> <qH5V8-7UF-3@gated-at.bofh.it>
Organization	Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

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On Fri, Dec 18, 2015 at 05:10:31PM +0100, Benjamin Tissoires wrote:
> After turning this around, I think I finally got what was going on (and
> yes, it's basically a race that should have been caught long ago):
> - during resume, the i2c-hid driver calls reset, which is a long (few
>   ms) operation.
> - hid-multitouch is also called during resume, and right after i2c-hid
> - hid-multiotuch immediately emits for touchpads a set input mode (this
>   was unseen with touchscreens because they do not have to be switched
>   into a proper mode)
> - there is a race between hid-multitouch accessing the features while
>   the device is still resetting. And our reset interrupt never gets to
>   us because there was an other operation in progress to request/set
>   reports
> 
> So the actual fix would be to make hid-multitouch wait until we reset
> i2c-hid.

The driver used for touchpad is actually hid-rmi but you are right, it
tries to set rmi mode (or something) during its rmi_post_reset() that
then confuses the i2c-hid driver.

Thanks for the analysis :-)

> This should be done by either a mutex or a spinlock in
> i2c_hid_output_raw_report() and i2c_hid_resume() that would protect a
> flag set during suspend and cleared after resume.

Makes sense. I'll make a patch that does this and submit it soon.
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Thread

[RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-15 20:20 +0100
  Re: [RESEND] Lenovo Yoga 900 touchpad issues Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-16 10:30 +0100
    Re: [RESEND] Lenovo Yoga 900 touchpad issues Jiri Kosina <jikos@kernel.org> - 2015-12-16 14:20 +0100
      Re: [RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-17 00:00 +0100
        Re: [RESEND] Lenovo Yoga 900 touchpad issues Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2015-12-17 11:00 +0100
          Re: [RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-17 18:00 +0100
            Re: [RESEND] Lenovo Yoga 900 touchpad issues Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2015-12-17 18:30 +0100
              Re: [RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-17 18:40 +0100
    Re: [RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-17 00:00 +0100
      Re: [RESEND] Lenovo Yoga 900 touchpad issues Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-18 15:50 +0100
        Re: [RESEND] Lenovo Yoga 900 touchpad issues Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-18 16:50 +0100
          Re: [RESEND] Lenovo Yoga 900 touchpad issues Benjamin Tissoires <benjamin.tissoires@redhat.com> - 2015-12-18 17:20 +0100
            Re: [RESEND] Lenovo Yoga 900 touchpad issues Mika Westerberg <mika.westerberg@linux.intel.com> - 2015-12-21 12:40 +0100
          Re: [RESEND] Lenovo Yoga 900 touchpad issues Nish Aravamudan <nish.aravamudan@gmail.com> - 2015-12-18 19:00 +0100

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