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

Chris Wilson
2017-02-17T11:43:23Z

On Fri, Feb 17, 2017 at 01:35:15PM +0200, Mika Kuoppala wrote:
> Chris Wilson <chris@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@chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala@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