[Intel-gfx] [PATCH v3] drm/i915: handle uncore spinlock when not available

[Vivi, Rodrigo]

> > 
> > Any other suggestions?
> 
> I think it will boil down to the reason uncore lock is held over the 
> respective sections ie. the comment in i915_get_crtc_scanoutpos.
> 
> If it is timing sensitive to the extent irq off was needed it may
> apply 
> to Xe as well. Likewise the need to use mmio helpers which rely on
> the 
> uncore lock already held. Question of whether there is conceptual 
> commonality, will probably drive the best name, or the best approach
> in 
> general.

yeap, this is how I'm seeing this. If i915-display needs this global
lock around mmio operations, then we wound need to add it to the
xe_mmio as well and then solve the name, etc.

However, I don't believe that other users of the mmio would need
this lock. So I believe the right thing to do is to create a i915-
display only spin_lock, around the intel_de_mmio calls and here.

With this we entirely kill the dependency on someone-else's lock
and have something that is entirely inside display code so it
doesn't need to be ported to one or another driver core components.

> 
> Regards,
> 
> Tvrtko