[Intel-gfx] [PATCH v2] drm/i915/execlists: Ensure arbitration is disabled for the breadcrumb

[Chris Wilson]

Quoting Chris Wilson (2019-05-02 15:17:01)
> If we interrupt building of the request, we may emit a request with no
> payload at all, with the consequence that we never disable arbitration
> prior to the breadcrumb. If we get preempted during the breadcrumb, it
> appears possible to lose the association of the interrupt with
> breadcrumb, and under the right conditions miss the breadcrumb interrupt
> entirely, leaving the request's waiters dangling.
> 
> Now that we always disable the arbitration in the breadcrumb, we can
> remove the redundant command to disable it after emitting the batch.
> 
> Testcase: igt/gem_concurrent_blit
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

That's not it either. Next idea?
-Chris