[Intel-gfx] [PATCH 04/15] drm/i915: Flush the execlist ports if idle

[Chris Wilson]

Quoting Mika Kuoppala (2017-07-20 13:18:40)
> > diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> > index 3c83f2dd6798..ad61d1998fb7 100644
> > --- a/drivers/gpu/drm/i915/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/intel_lrc.c
> > @@ -1327,6 +1327,31 @@ static void reset_common_ring(struct intel_engine_cs *engine,
> >  {
> >       struct execlist_port *port = engine->execlist_port;
> >       struct intel_context *ce;
> > +     unsigned int n;
> > +
> > +     /*
> > +      * Catch up with any missed context-switch interrupts.
> > +      *
> > +      * Ideally we would just read the remaining CSB entries now that we
> > +      * know the gpu is idle. However, the CSB registers are sometimes^W
> > +      * often trashed across a GPU reset! Instead we have to rely on
> > +      * guessing the missed context-switch events by looking at what
> > +      * requests were completed.
> > +      */
> > +     if (!request) {
> > +             for (n = 0; n < ARRAY_SIZE(engine->execlist_port); n++)
> 
> You need to check against null before put in here?

dma_fence_put and i915_gem_request_put, by extension, are NULL-safe.
-Chris