[Intel-gfx] [PATCH 06/19] drm/i915: Enable i915_gem_wait_for_idle() without holding struct_mutex

[Joonas Lahtinen]

On pe, 2016-08-05 at 07:51 +0100, Chris Wilson wrote:
> On Fri, Aug 05, 2016 at 09:16:21AM +0300, Joonas Lahtinen wrote:
> > 
> > On to, 2016-08-04 at 20:52 +0100, Chris Wilson wrote:
> > > 
> > > @@ -486,7 +486,8 @@ void __i915_add_request(struct drm_i915_gem_request *request,
> > >  	 */
> > >  	request->emitted_jiffies = jiffies;
> > >  	request->previous_seqno = engine->last_submitted_seqno;
> > > -	smp_store_mb(engine->last_submitted_seqno, request->fence.seqno);
> > > +	engine->last_submitted_seqno = request->fence.seqno;
> > What's up with this change?
> Where we use to use an ordered store of the last seqno for checking
> idleness inside hangcheck, we now use the RCU active tracking instead.
> 
> engine->last_submitted_seqno is reduced to a heuristic used for debug
> (gpu error state) and for deciding when to grant a fresh waitboost.

Makes sense, put that to commit message and;

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation