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

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-07-22 09:12:14)
> 
> On 20/07/2020 16:02, Chris Wilson wrote:
> > 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.
> 
> You think it's not as simple as early return in arm if on irq engine?

And moving the early checks to disarm_irq for symmetry. I was just
worrying too much about the impact of changing irq_armed.
-Chris