[PATCH] drm: vc4: Don't wait for vblank when updating the cursor

[Michael Zoran]

On Tue, 2017-02-28 at 16:42 +0900, Michel Dänzer wrote:
> On 24/02/17 10:54 AM, Michael Zoran wrote:
> > Commonly used desktop environments such as xfce4 and gnome
> > on debian sid can flood the graphics drivers with cursor
> > updates.
> 
> FWIW, this has nothing to do with the desktop environment or indeed
> the
> client side at all. Translating input to HW cursor movement is
> handled
> entirely inside the X server.
> 
> 

Yes, as your point out it may well be the x server that is causing
this.  I wasn't sure if it was the windows manager or the x server that
was doing this.

Either way, when opening a new application the driver gets flooded with
cursor updates as something is animating a spinning cursor.  Since the
refresh rate is only 60Hz, I see a very long hang in the
desktop(several minutes) where nothing responds.  SSHing into the RPI
still works though even though it appears hung.

I had a few people on the net test the changes and they all report that
without the change xfce4 and gnome are both unusable on the RPI.  With
the change, things work fine.  Not waiting for the vblank on cursor
updates is what other drivers appears to do as well...