[Intel-gfx] [PATCH] intel: fix fullscreen damage posting on pageflip

[Chris Wilson]

On Thu, 11 Oct 2012 14:30:29 +1000, Dave Airlie <airlied at gmail.com> wrote:
> From: Dave Airlie <airlied at redhat.com>
> 
> While playing with MPX and sw cursor I noticed page flips won't
> end up misrendering some bits, so the sw cursor was replacing the
> bits on the wrong pixmap.
> 
> Fix the damage handling to be correct and append damage before swapping
> the pointers and process damage after.
> 
> This fixes misrendering with MPX cursors under a fullscreen compositor,
> that pageflips.

Wow, what magic is this? The created region is the same and
front->drawable left unmodified by the exchange. The exchange only
manipulates the devPrivates and has not other side effects. The only
uncertain quantity there is the intel_glamor_exchange_buffers()...

So the change is that we append the same damage to the same drawable
earlier, yet still process that damage at the same time, with no
apparent side-effects between the two operations. I'm just not
understanding why this has any effect.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre