agd5f

For those of you with rs780 chips wanting to try the new EXA/Xv accel, I’ve sorted out the hanging issues.  You’ll need the latest bits from the r6xx-r7xx-accel branches of both the drm and radeonhd.  I’ve also fixed a hang on r7xx chips due to the way you have to do SQ constant updates; this may help rv670/680 users as well.

It took a while, but I think this is a solid release.  New features include:
- Bicubic Xv scaling on r3xx/r4xx/r5xx/rs690
- Support for new asics
- Reduced tearing with Xv (more info)
- EXA Stability improvements
and of course lots of bug fixes.

See the git log for the full list of changes.  Many thanks to all involved!