Re: i2c designware change broke touchpad of a thinkpad

[johannes.goede@oss.qualcomm.com]

Hi Thorsten,

On 17-Aug-26 1:12 PM, Thorsten Leemhuis wrote:
> On 8/17/26 11:51, johannes.goede@oss.qualcomm.com wrote:
>> On 14-Aug-26 12:09 PM, Hardik Prakash wrote:
>>> On Wed, 13 Aug 2026, Thorsten Leemhuis wrote:
>>>> Hardik, could you submit a revert to the lists? And then I'll provide my
>>>> Tested-by and ask Linus to directly pick this up?
>>>
>>> Sent: https://lore.kernel.org/all/20260814100719.9548-1-hardikprakash.official@gmail.com/
>>>
>>> Verified on my end that it builds clean, boots clean, and correctly
>>> restores the original Yoga 7 race (expected tradeoff) without
>>> introducing anything else.
> 
> Hans, thx for looking into this.
>> Thank you for submitting a revert for this. Note it looks like Torvalds himself
>> beat you to it and already reverted this for 7.2 final :)
> 
> Yeah, I pointed Linus to this and a few others issues and then he
> reverted the change directly:
> https://lore.kernel.org/all/628bbf10-29f1-4e9e-b23b-4c47657433b9@leemhuis.info/
> 
>> I hit another problem caused by this now reverted change, where the PMIC
>> i2c bus would not show up on many Intel BYT/CHT devices. I wrote a fix for
>> this (attached) on top of the now reverted commit.
> 
> FWIW, meanwhile "Tran Tien Dat" (now CCed) with -next ran into a problem
> on a MSI Modern 14 H D13MG that the revert seems to have resolved. But
> the symptoms were different: the two DesignWare I2C controllers in that
> machine apparently deferred probe forever and are never retried:
> 
> 16.429266 platform i2c_designware.1: deferred probe pending: (reason
> unknown)
> 16.429286 platform i2c_designware.0: deferred probe pending: (reason
> unknown)

Right, that is actually the same thing which my patch (on top of the
non-reverted original commit) addresses on BYT / CHT devices.

When I wrote "the PMIC i2c bus would not show up" I meant that
the i2c-controller for that bus would never get registered with
the kernel because of the probe being deferred forever.

Regards,

Hans