Re: [REGRESSION] drm/xe/guc: Lenovo Thinkpad X1 Carbon Gen 12 can't boot with 6.16.9 and Xe driver

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 9/28/2025 8:40 AM, Sasha Levin wrote:
> On Sun, Sep 28, 2025 at 01:16:34PM +0200, Iyán Méndez Veiga wrote:
>> On 27/09/2025 16:31, Thorsten Leemhuis wrote:
>>> Thx. Could you also try if reverting the patch from 6.16.y helps? Note,
>>> you might need to revert "drm/xe/guc: Set RCS/CCS yield policy" as 
>>> well,
>>> which apparently depends on the patch that causes your problems.
>>
>> Yes, reverting both dd1a415dcfd5 "drm/xe/guc: Set RCS/CCS yield 
>> policy" and 97207a4fed53 "drm/xe/guc: Enable extended CAT error 
>> reporting" from 6.16.y fixes the issue for me.
>
> Thanks for the report and investigation!
>
> I'll revert these two.
>

Hi,

Thanks for the bisect and the quick turnaround on this (and sorry for 
not replying earlier, I just came back from vacation :) ).
Just wanted to add a quick comment as the author of both patches. I have 
no idea why these patches would cause issues on 6.16 but not on 6.17, 
nothing significant should be different between the two releases in the 
impacted area. However, no one has actually ever reported hitting the 
starvation issue mitigated by the RCS/CCS patch (which has been there 
since 6.13), likely because it can only be reproduced if the GPU is 
heavily overloaded by multiple apps; therefore, given that 6.16 is not 
an LTS, I'm not going to attempt to reproduce and debug this and re-send 
the patches for that kernel version.
Please let me know if there are any concerns with this approach or if 
the issue pops up on 6.17.

Thanks
Daniele