Re: [PATCH 7.1 00/21] 7.1.2-rc1 review

["Barry K. Nathan" <barryn@pobox.com>]

On 6/26/26 5:31 PM, Dmitry Torokhov wrote:
> On Fri, Jun 26, 2026 at 03:23:12PM -0700, Barry K. Nathan wrote:
>> On 6/26/26 2:17 PM, Dmitry Torokhov wrote:
>>> On Fri, Jun 26, 2026 at 01:41:38PM -0700, Barry K. Nathan wrote:
>>>> On 6/26/26 12:56 PM, Dmitry Torokhov wrote:
>>>>> Hi Barry,
>>>>>
>>>>> On Fri, Jun 26, 2026 at 10:56:21AM -0700, Barry K. Nathan wrote:
>>>>>> (cc Dmitry Torokhov because this is related to two of your commits)
>>>>>>
>>>>>> On 6/25/26 6:03 AM, Greg Kroah-Hartman wrote:
>>>>>>> This is the start of the stable review cycle for the 7.1.2 release.
>>>>>>> There are 21 patches in this series, all will be posted as a response
>>>>>>> to this one.  If anyone has any issues with these being applied, please
>>>>>>> let me know.
>>>>>>>
>>>>>>> Responses should be made by Sat, 27 Jun 2026 12:54:50 +0000.
>>>>>>> Anything received after that time might be too late.
>>>>>>>
>>>>>>> The whole patch series can be found in one patch at:
>>>>>>> 	https://www.kernel.org/pub/linux/kernel/v7.x/stable-review/patch-7.1.2-rc1.gz
>>>>>>> or in the git tree and branch at:
>>>>>>> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-7.1.y
>>>>>>> and the diffstat can be found below.
>>>>>>>
>>>>>>> thanks,
>>>>>>>
>>>>>>> greg k-h
>>>>>>>
>>>>>> Unfortunately, 7.1.2-rc1 breaks the Synaptics touchpad on my Lenovo
>>>>>> ThinkPad T14 Gen 1 -- the pointer no longer moves when I touch the
>>>>>> touchpad. Potentially relevant line from dmesg:
>>>>>>
>>>>>> rmi4_f01 rmi4-00.fn01: found RMI device, manufacturer: Synaptics, product: TM3471-020, fw id: 3972349
>>>>>>
>>>>>>> Dmitry Torokhov<dmitry.torokhov@gmail.com>
>>>>>>>         Input: rmi4 - refactor register descriptor parsing
>>>>>>>
>>>>>>> Dmitry Torokhov<dmitry.torokhov@gmail.com>
>>>>>>>         Input: rmi4 - fix register descriptor address calculation
>>>>>>>> Both of these patches seem bad in my testing. Either one, individually,
>>>>>> causes the pointer to no longer move when I touch the touchpad. If I
>>>>>> revert both of them, then my touchpad works again.
>>>>>>
>>>>>> I have not yet tested 7.0.14-rc1 or 6.18.37-rc1. However, the problem
>>>>>> also reproduces on current mainline as of this writing (commit
>>>>>> 51cb1aa1250c36269474b8b6ca6b6319e170f5a5).
>>>>> Could you please try applying this debug patch and send me dmesg?
>>>> Sure, I applied the patch on top of mainline, and the dmesg output is
>>>> below.
>>> Thank you! So I messed up and "Input: rmi4 - fix register descriptor
>>> address calculation" is totally wrong.
>>>
>>> Can you please revert it (keeping the debug patch) and try booting again
>>> and if the touchpad still does not work post the dmesg again.
>>>
>>> Thanks!
>>
>> I did the revert, while keeping the debug patch. With this kernel, the
>> touchpad still doesn't work for me, so here's the new dmesg.
> 
> Thank you. It looks like the firmware is a bit sloppy and the new
> tightened checks are tripping on it. Please try this patch:
> 
> 
> Input: rmi4 - tolerate short register descriptor structure
> 
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> 
> Some touchpads (e.g. ThinkPad T14 Gen 1) have buggy firmware that reports
> a register descriptor structure size that is too small for the number of
> registers it claims to have in the presence map. The remaining bytes in
> the structure are 0, which with the new strict bounds checking causes the
> parser to fail with -EIO, aborting the device probe.
> 
> Tolerate such short reads by dropping the remaining (unparseable or
> 0-size) registers from the list instead of failing the probe,
> preventing the driver from trying to use them.
> 
> Fixes: 0adb483fbf2d ("Input: rmi4 - refactor register descriptor parsing")
> Reported-by: Barry K. Nathan <barryn@pobox.com>
> Cc: stable@vger.kernel.org
> Assisted-by: Antigravity:gemini-3.5-flash
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Yes, this worked! To be clear, what I did (and what I'm successfully
running now) is:

1. Start with mainline as of commit 51cb1aa1250c36269474b8b6ca6b6319e170f5a5
2. Then revert a98518e72439fd42cbfe641c2896543cb088e3d1
    ("Input: rmi4 - fix register descriptor address calculation")
3. Then apply the new patch
    ("Input: rmi4 - tolerate short register descriptor structure")

If there's anything else I need to test or anything else you want me
to try, please let me know. Thank you!

-- 
-Barry K. Nathan  <barryn@pobox.com>