[Intel-gfx] [PATCH] drm/i915/gt: Temporarily force MTL into uncached mode

[Tvrtko Ursulin]

On 10/10/2023 17:17, Andi Shyti wrote:
> Hi Matt,
> 
>>>>> FIXME: CAT errors are cropping up on MTL.  This removes them,
>>>>> but the real root cause must still be diagnosed.
>>>>
>>>> Do you have a link to specific IGT test(s) that illustrate the CAT
>>>> errors so that we can ensure that they now appear fixed in CI?
>>>
>>> this one:
>>>
>>> https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_124599v1/bat-mtlp-8/igt@i915_selftest@live@hugepages.html
>>>
>>> Andi
>>
>> Wait, now I'm confused.  That's a failure caused by a different patch
>> series (one that we won't be moving forward with).  The live at hugepages
>> test is always passing on drm-tip today:
>> https://intel-gfx-ci.01.org/tree/drm-tip/igt@i915_selftest@live@hugepages.html
> 
> yes, true, but that patch allows us to move forward with the
> testing and hit the CAT error.
> 
> (it was the most reachable link I found :))
> 
>> Is there a test that's giving CAT errors on drm-tip itself (even
>> sporadically) that we can monitor to see the impact of Jonathan's patch
>> here?
> 
> Otherwise this one:
> 
> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_13667/re-mtlp-3/igt@gem_exec_fence@parallel.html#dmesg-warnings11

Parachuting in on a tangent - please do not mix CAT and CT errors. CAT, for me at least, associates with CATastrophic faults reported over CT channel, like GuC page faulting IIRC.

For CT errors maybe GuC folks can sched some light what they mean.

Regards,

Tvrtko