[Intel-gfx] [PATCH] drm/i915: Check fence status after serialising with the spinlock

[Joonas Lahtinen]

On pe, 2017-01-27 at 13:06 +0000, Chris Wilson wrote:
> A very rare problem we encounter is that as retire the request we find
                                         we -^
> that it appears to not have been yet executed. Other than malevolent hw,
> one possible explanation is that the update of the fence status on one
> cpu (an atomic_dec_and_test) is not yet visible to the retiree on
> another cpu. However, since retirement is serialised with execution via
> a fence-local spinlock, we can use these to ensure that we have

But it uses timeline spinlock?

> sufficient barriers between the execution and the assert in retirement.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation