[PATCH] Xv: Fix AdjustFrame when driver implements ReputImage.

[Keith Packard]

On Thu, 26 Nov 2009 01:06:16 +0100, Luc Verhaegen <libv at skynet.be> wrote:
> On Wed, Nov 11, 2009 at 03:59:27PM +0100, Luc Verhaegen wrote:
> > Should probably also be applied to stabler xserver branches too.
> > 
> > Luc Verhaegen.
> 
> 2 week bump, for something that fixes a 4 year old bug.

I suspect the fact that the underlying code is twisty and
incomprehensible may have made people reluctant to even try and review
this patch.

I spent a few minutes looking at the code and it looks good to me, in
particular, the patch makes the code look more sensible.

XV_PENDING is set when trying to do a video operation and the output is
completely clipped or failed for some other reason (line 744, 835, 922,
1491, 1606 and 1794). It is also set when the window is exposed and the
driver doesn't provide a ReputImage function (line 1083), or when the
window becomes invisible during ClipNotify (line 1137), or becomes
FullyObscured in AdjustFrame (line 1318).

XV_PENDING appears to be an indication that video *should* be presented,
but just isn't because the driver has returned an error or because the
window is fully obscured. So, every time the window becomes more
visible, we should try to make it no longer XV_PENDING.

The patch simply makes the AdjustFrame code actually look at XV_PENDING
windows and, if the window is not fully obscured, calls ReputImage to
get bits on the screen. The second change in the patch handles the XV_ON
case (now that the block includes both XV_ON and XV_PENDING) separately,
setting the port to XV_PENDING if the window is now fully obscured.

One case which wasn't clear when I started reading the code was whether
xf86XVReputImage would handle XV_PENDING ports correctly; reading that
code, it looks like it will work as it sets portPriv->isOn along every
potential code path.

So, with that,

Reviewed-by: Keith Packard <keithp at keithp.com>

-- 
keith.packard at intel.com
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