[Intel-gfx] [PATCH 2/2] drm/i915: Add WaKBLVECSSemaphoreWaitPoll

[Mika Kuoppala]

Joonas Lahtinen <joonas.lahtinen at linux.intel.com> writes:

> Quoting Mika Kuoppala (2018-06-05 19:03:57)
>> There is a problem with kbl up to rev E0 where a heavy
>> memory/fabric traffic from adjacent engine(s) can cause an engine
>> reset to fail. This traffic can be from normal memory accesses
>> or it can be from heavy polling on a semaphore wait.
>> 
>> For engine hogging causing a fail, we already fallback to
>> full reset. Which effectively stops all engines and thus
>> we only add a workaround documentation.
>> 
>> For the semaphore wait loop poll case, we add one microsecond
>> poll interval to semaphore wait to guarantee bandwidth for
>> the reset preration. The side effect is that we make semaphore
>> completion latencies also 1us longer.
>> 
>> v2: Let full reset handle the adjacent engine idling (Chris)
>> 
>> References: https://bugs.freedesktop.org/show_bug.cgi?id=106684
>> References: VTHSD#2227190, HSDES#1604216706, BSID#0917
>> Signed-off-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
>
> Skip the RCS engine and this is;
>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

RCS engine skipped on v2, and both patches pushed.
Thank you both for review.
-Mika