APPLIED[Unstable] / Cmt: [SRU] [B/C/D/Unstable] [PATCH 0/2] Fix and issue that LG I2C touchscreen stops working after reboot

Kai Heng Feng kai.heng.feng at
Thu Nov 29 05:14:47 UTC 2018

> On Nov 28, 2018, at 12:36 AM, Seth Forshee <seth.forshee at> wrote:
> On Tue, Nov 27, 2018 at 06:59:06AM +0000, Kai-Heng Feng wrote:
>> BugLink:
>> [Impact]
>> LG I2C touchscreen stops working after reboot.
>> [Fix]
>> Disable runtime PM for the touchscreen, which doesn't work well with
>> consecutive ON/SLEEP commands.
>> [Test]
>> The touchscreen works well after reboot, when runtime PM is disabled.
>> [Regression Potential]
>> None. This is a new device and the fix is limited to this particular
>> device.
> The patch did not apply to unstable, so I cherry picked the fix
> directly.


> Wrt bionic though, there's the extra prerequisite patch that looks to be
> affecting a different touchscreen. If so you can't really say that the
> regression potential is limited to a single device. You should either
> explain why we should also change runtime PM for that device and
> describe what regression testing was done, or else omit the changes for
> that device.

I missed that one, sorry. It does introduce a fix for another device.

The change to runtime PM is to let the driver never tries to runtime
suspend the device, avoiding sending too many ON/SLEEP command to
the device.


> Thanks,
> Seth

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