Slow 2D with radeon KMS

[Damien Mir]

> vsync was broken when intel merged the new vsync code. So you should
> use mesa from time before the merge (about a week ago)
>

Unfortunately I cannot get vsync working anyhow with Kwin compositing (KDE
4.3).

Any combination of xserver (1.6 / 1.7 / 1.7.99) / Mesa (7.7 or git) gives
the same results on an R700 HD4650 mobility.

Any idea on what's going on ? Sorry if it's a bit OT, but does it seem
related to the R700/xorg/mesa mix ? or might it be something completely
different ?
Because being unable to play tear-free videos quite kills a nice
compositing experience !
Note : Xv playback is tear-free with kwin compositing disabled