[Intel-gfx] [PATCH v4] drm/i915/guc: Stop using mutex while sending CTB messages

[Chris Wilson]

Quoting Michal Wajdeczko (2020-02-03 11:07:24)
> 
> >> +               /* CTB_RECV lock will be used with irq disabled */
> >
> > ...will be used inside the interrupt handler
> >
> > I think is a more descriptive comment.
> 
> Well, we usually call intel_guc_ct_event_handler() from irq handler,
> but we are also calling it from guc_enable_communication(), that's
> outside irq handler (but with irq disabled)

I think the sole reason for the distinction between the two cases is that
only RECV is used from interrupt paths (we could always reorder the
guc_enable_communication if that was not the case). That I think
explains why keeping the two locks separate is important (or more
nuanced than usual).
-Chris