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Date:      Tue, 10 Sep 2019 23:08:53 +0000
From:      bugzilla-noreply@freebsd.org
To:        bugs@FreeBSD.org
Subject:   [Bug 240339] [ig4] I2C2 (touchpad bus) broken on the Google Pixelbook (Sunrise Point PCH)
Message-ID:  <bug-240339-227-drPHsXhVby@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-240339-227@https.bugs.freebsd.org/bugzilla/>
References:  <bug-240339-227@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D240339

--- Comment #9 from Greg V <greg@unrelenting.technology> ---
(In reply to Vladimir Kondratyev from comment #7)

oh cool, you already wrote the ACPI lookup of parameters, I was thinking ab=
out
doing that haha. Though the values that it ends up applying seem really high
(564, 480 on i2c2 for SCL). I commented that out again

Unfortunately the problem is still there.

Some more testing:

- after the lockup in FreeBSD, Linux cannot recover that i2c bus either =E2=
=80=94
rebooting (not shutting down and powering up) into Chrome OS results in
'i2c_designware.2: controller timed out' and the touchpad not working;

- the EC interface on the same bus allows reading the console of the touchp=
ad's
firmware, but that's impossible when the controller is locked up.. I'm wait=
ing
for a debug cable to ship, but the documentation doesn't say that it's poss=
ible
to access the touchpad console through that;

- I added some logging to the error handling, on i2c0 (working touchscreen)
after reading the touchscreen's descriptor for setup there's an RX underflo=
w,
but here (touchpad) that did not happen, none of these errors happened;

- with HAVE_IG4_POLLING in iichid, there's no RX underflow there (obviously=
),
but it does not fix the lockup.

I wonder if it might actually be iichid/imt doing something that causes the
touchpad to do something wrong with the bus=E2=80=A6

log: https://gist.github.com/myfreeweb/67b3ca690c22b31f502079b11263f0f4

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