[Intel-gfx] [PATCH v2 3/3] drm/i915: Defer declaration of missed-interrupt until the waiter is asleep

[Chris Wilson]

On Fri, Feb 17, 2017 at 01:35:15PM +0200, Mika Kuoppala wrote:
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > If the waiter was currently running, assume it hasn't had a chance
> > to process the pending interupt (e.g, low priority task on a loaded
> > system) and wait until it sleeps before declaring a missed interrupt.
> >
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=99816
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_breadcrumbs.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> > index 4395b177493e..2ad29fb77b2d 100644
> > --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> > +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> > @@ -45,6 +45,15 @@ static void intel_breadcrumbs_hangcheck(unsigned long data)
> >  		return;
> >  	}
> >  
> > +	/* If the waiter was currently running, assume it hasn't had a chance
> > +	 * to process the pending interupt (e.g, low priority task on a loaded
> > +	 * system) and wait until it sleeps before declaring a missed interrupt.
> > +	 */
> > +	if (!intel_engine_wakeup(engine)) {
> 
> But this will happen if there is waiter running, or that there is
> no waiter at all.
> 
> Don't we need to exclude the latter?

We already exclude the latter by cancelling this timer above.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre