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

[Matt Roper]

On Tue, Oct 10, 2023 at 05:42:28PM +0100, Tvrtko Ursulin wrote:
> 
> 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.

0x6000 is GUC_ACTION_GUC2HOST_NOTIFY_MEMORY_CAT_ERROR so this actually
is a CAT error, delivered via the CT channel.


Matt

> 
> Regards,
> 
> Tvrtko

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation