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

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> 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>
>

Pushed to drm-intel-next-queued. Thanks.
-Mika