[Intel-gfx] [PATCH 2/2] drm/i915/skl: Fix spurious gpu hang with gt3/gt4 revs

[Mika Kuoppala]

Ben Widawsky <benjamin.widawsky at intel.com> writes:

> [ text/plain ]
> On Tue, Apr 05, 2016 at 03:56:17PM +0300, Mika Kuoppala wrote:
>> Experiments with heaven 4.0 benchmark and skylake gt3e (rev 0xa)
>> suggest that WaForceContextSaveRestoreNonCoherent is needed for all
>> revs. Extending this to all revs cures a gpu hang with rev 0xa when
>> running heaven4.0 gpu benchmark.
>> 
>> We have been here before, with problems enabling gt4e and extending
>> up to revision F0 instead of false claims of bspec of E0 only. See
>> commit <e238659ddd88> ("drm/i915/skl: Default to noncoherent access
>> up to F0"). In retrospect we should have covered this with this big
>> blanket back then already, as E0 vs F0 discrepancy was suspicious
>> enough.
>> 
>> Previously the WaForceEnableNonCoherent has been tied to
>> context non-coherence, atleast in relevant hsds. So keep this tie
>> and extended this alongside.
>> 
>> Cc: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
>> Cc: Ben Widawsky <benjamin.widawsky at intel.com>
>> Cc: Timo Aaltonen <tjaalton at ubuntu.com>
>> Cc: stable at vger.kernel.org
>> Reported-by: Mike Lothian <mike at fireburn.co.uk>
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=93491
>> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
>
> I don't have a reproducible hang, but both are:
> Reviewed-by: Ben Widawsky <benjamin.widawsky at intel.com>
>

Both patches pushed to dinq. Thanks for review and testing.

-MIka

> -- 
> Ben Widawsky, Intel Open Source Technology Center