[Intel-gfx] [PATCH 1/2] drm/i915: Make sure engines are idle during GPU idling in LR mode

[Chris Wilson]

On Fri, Nov 04, 2016 at 10:33:24PM +0200, Imre Deak wrote:
> On Thu, 2016-11-03 at 21:14 +0000, Chris Wilson wrote:
> > Where is that guaranteed? I thought we only serialised with the pm
> > interrupts. Remember this happens before rpm suspend, since
> > gem_idle_work_handler is responsible for dropping the GPU wakelock.
> 
> I meant that the 100msec after the last request signals completion and
> this handler is scheduled is normally enough for the context complete
> interrupt to get delivered. But yea, it's not a guarantee.

If only it was that deterministic! The idle_worker was scheduled 100ms
after some retire_worker, just not necessarily the most recent. So it
could be running exactly as active_requests -> 0 and so before the
context-interrupt.

Anyway, it was a good find!
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre