[Intel-gfx] [PATCH 01/20] drm/i915: Skip barriers inside waits

[Andi Shyti]

Hi Cris,

> Attaching to the i915_active barrier is a two stage process, and a flush
> is only effective when the barrier is activation. Thus it is possible
> for us to see a barrier, and attempt to flush, only for our flush to
> have no effect. As such, before attempting to activate signaling on the
> fence we need to double check it is a fence!
> 
> Fixes: d13a31770077 ("drm/i915: Flush idle barriers when waiting")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Reviewed-by: Andi Shyti <andi.shyti at intel.com>

Andi