[Intel-gfx] [PATCH] drm/i915/execlists: Remove the ring advancement under preemption

[Chris Wilson]

Quoting Michel Thierry (2018-02-21 17:25:54)
> On 21/02/18 05:32, Chris Wilson wrote:
> > Load an empty ringbuffer for preemption, ignoring the lite-restore
> > workaround as we know the preempt context is always idle before preemption.
> > 
> 
> True, injecting the preempt context shouldn't cause a lite-restore.
> And the restriction was to always have Head!=Tail when attempting lite 
> restore.
> 
> > Note that after some digging by Michal Winiarski, we found that
> > RING_HEAD is no longer being updated (due to inhibiting context save
> > restore) so this patch is already in effect!
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Michal Winiarski <michal.winiarski at intel.com>
> > Cc: Michel Thierry <michel.thierry at intel.com>
> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> 
> Reviewed-by: Michel Thierry <michel.thierry at intel.com>

And pushed. Thanks for the review, at worst this just shows that we have
an issue more readily :)
-Chris