[Intel-gfx] [PATCH 13/14] drm/i915/guc: Workaround the missing user interrupt after preemption

[Chris Wilson]

Quoting Chris Wilson (2017-10-19 20:44:41)
> Quoting Michał Winiarski (2017-10-19 19:36:18)
> > With GuC, we're scheduling tasklet on USER_INTERRUPT - since some work
> > has completed, perhaps we're able to submit some more work. We're doing
> > similar thing for preemption - after preemption has completed, it's time
> > to schedule the tasklet and submit more work (since the engine is now
> > idle). Unfortunately, we can hit the scenarios where the preemption is
> > done, but the interrupt is nowhere to be seen. To work around the
> > problem, let's use a delayed work that's kicking the tasklet if
> > preemption is done, and queueing itself otherwise.
> 
> I'm not buying it yet.

I think I know what it is. I think it is as simple as us turning off the
irq when there's no more requests being signaled on the engine.
-Chris