[Intel-gfx] [PATCH] drm/i915/gt: Ignore irq enabling on the virtual engines

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-07-13 11:19:58)
> 
> On 11/07/2020 21:32, Chris Wilson wrote:
> > We do not use the virtual engines for interrupts (they have physical
> > components), but we do use them to decouple the fence signaling during
> > submission. Currently, when we submit a completed request, we try to
> > enable the interrupt handler for the virtual engine, but we never disarm
> > it. A quick fix is then to mark the irq as enabled, and it will then
> > remain enabled -- and this prevents us from waking the device and never
> > letting it sleep again.
> > 
> > Fixes: f8db4d051b5e ("drm/i915: Initialise breadcrumb lists on the virtual engine")
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: <stable at vger.kernel.org> # v5.5+
> > ---
> >   drivers/gpu/drm/i915/gt/intel_lrc.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > index cd4262cc96e2..504e269bb166 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > @@ -5727,6 +5727,7 @@ intel_execlists_create_virtual(struct intel_engine_cs **siblings,
> >       intel_engine_init_active(&ve->base, ENGINE_VIRTUAL);
> >       intel_engine_init_breadcrumbs(&ve->base);
> >       intel_engine_init_execlists(&ve->base);
> > +     ve->base.breadcrumbs.irq_armed = true;
> 
> Add a comment here saying this is a hack and why please. With that:

"This is a lot simpler than splitting breadcrumbs, although we do need
to do that. But that was becoming a very hairy patch."
-Chris