[Intel-gfx] [PATCH] drm/i915: Fix system hang with EI UP masked on Haswell

[Chris Wilson]

On Thu, Apr 13, 2017 at 02:15:27PM +0300, Mika Kuoppala wrote:
> Previously with commit a9c1f90c8e17
> ("drm/i915: Don't mask EI UP interrupt on IVB|SNB") certain,
> seemingly unrelated bit (GEN6_PM_RP_UP_EI_EXPIRED) was needed
> to be unmasked for IVB and SNB in order to prevent system hang
> with chained batchbuffers.
> 
> Our CI was seeing incomplete results with tests that used
> chained batches and it was found out that HSW needs to have this
> same bit unmasked to reliably survive chained batches.
> 
> Always unmask GEN6_PM_RP_UP_EI_EXPIRED on Haswell to
> prevent system hang with batch chaining.
> 
> Testcase: igt/gem_exec_fence/nb-await-default
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100672
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: stable at vger.kernel.org
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

* facepalm.

I am amazed that took so long for us to notice.
Acked-by: Chris Wilson <chris at chris-wilson.co.uk>

Did we ever get a w/a identifier for this?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre