Fix for GPU/CPU thrashing in DPMS off state

[Ilija Hadzic]

Hi,

The following patch set will fix the problem described in this
E-mail thread:

http://lists.x.org/archives/xorg-driver-ati/2012-December/024027.html

The first two patches are prep-patches and the do not change any
functionality to the driver. The third patch implements the fix
by using Xorg's timer facility to defer the swap when vblank
cannot be used for that purpose.

Regards,

Ilija