[PATCH] Add virtio gpu driver.

[Gerd Hoffmann]

  Hi,

> > Why attach the hotspot to the plane?  Wouldn't it make more sense to
> > make it a framebuffer property?
> 
> We don't have properties on the framebuffer. I guess you /could/ just add
> it internally to struct drm_framebuffer, and not bother exposing to
> userspace. I guess that would be a lot simpler,

Yes.  I can simply stick the hotspot into drm_framebuffer in
drm_mode_cursor_universal() and pick up the values in the driver's plane
update function.

>  but it also means that
> atomic userspace can't use hotspots before we add properties to fbs. And
> doing that is a bit tricky since drm_framebuffer objects are meant to be
> invariant - this assumption is deeply in-grained into the code all over
> the place, everything just compares pointers when semantically it means to
> compare the entire fb (including backing storage pointer/offsets and
> everything).

Hmm, the hotspot location for a given cursor image is invariant too, so
I don't think that would be a big issue.

I'd expect userspace define a bunch of cursors, then switch between them
(instead of defining a single cursor, then constantly updating it).

cheers,
  Gerd