[Intel-gfx] [PATCH 05/10] drm/i915/gt: Distinguish the virtual breadcrumbs from the irq breadcrumbs

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-07-20 12:23:35)
> 
> On 20/07/2020 10:23, Chris Wilson wrote:
> > -void intel_engine_init_breadcrumbs(struct intel_engine_cs *engine)
> > +struct intel_breadcrumbs *
> > +intel_breadcrumbs_create(struct intel_engine_cs *irq_engine)
> >   {
> > -     struct intel_breadcrumbs *b = &engine->breadcrumbs;
> > +     struct intel_breadcrumbs *b;
> > +
> > +     b = kzalloc(sizeof(*b), GFP_KERNEL);
> > +     if (!b)
> > +             return NULL;
> >   
> >       spin_lock_init(&b->irq_lock);
> >       INIT_LIST_HEAD(&b->signalers);
> >       INIT_LIST_HEAD(&b->signaled_requests);
> >   
> >       init_irq_work(&b->irq_work, signal_irq_work);
> > +
> > +     b->irq_engine = irq_engine;
> > +     if (!irq_engine)
> > +             b->irq_armed = true; /* fake HW, used for irq_work */
> 
> Disarm is checking for !b->irq_engine and arm asserts there must be when 
> arming. If instead arm would abort on !b->irq_engine would it all work 
> just as well without the need for this hack?

Yes, it is asymmetric. I thought keeping the asymmetry in place for the
conversion would be simpler, but didn't really make an attempt to make
irq_armed behave as one would expect.
-Chris