[Intel-gfx] [PATCH 6/8] drm/i915/guc: Keep the engine awake until the tasklet is idle

[Chris Wilson]

Quoting Daniele Ceraolo Spurio (2019-08-12 21:38:39)
> 
> 
> On 8/12/19 3:44 AM, Chris Wilson wrote:
> > Quoting Chris Wilson (2019-08-12 10:10:43)
> >> For the guc, we need to keep the engine awake (and not parked) and not
> >> just the gt. If we let the engine park, we disable the irq and stop
> >> processing the tasklet, leaving state outstanding inside the tasklet.
> >>
> >> The downside is, of course, we now have to wait until the tasklet is run
> >> before we consider the engine idle.
> > 
> > Fwiw, because of this I think it may be preferable to keep to using GT
> > pm for the tasklet; and apply Daniele's patch to keep
> > NEEDS_BREADCRUMB_TASKLET set (which is the right thing to do anyway now
> > that we stop switching between submission modes).
> > -Chris
> > 
> 
> Given that the GuC submission code is about to undergo a rework I 
> believe it'd be better to keep the fix contained to the GuC side of 
> things for now and avoid impacting the more general request paths (i.e. 
> patch 4 in this series, unless you still want that for other reasons). 
> I'll clean up and send the other patch.

Oh, we need that anyway :)
https://bugs.freedesktop.org/show_bug.cgi?id=111378

And it actually clarified some of the heartbeat code, so it's an
eventual win.
-Chris