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

[Tvrtko Ursulin]

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?

Regards,

Tvrtko