drm_crtc->fb may point to NULL, f.e X server will allocate a new fb
and assign it to the CRTC at startup, when X server exits, it will destroy
the allocated fb, making drm_crtc->fb points to NULL.
This should work on all radeon but there is still many things todo:
- add crtc2
- tmds
- lvds
- add bios data table so we don't need to hardcode dac/crtc infos
- separate clock control to make power saving easier & cleaner
- tiling (warning tiling shouldn't be enable in double scan or interlace)
- surface reg manager (this goes along with tiling)
- suspend/resume hook
- avivo & r500 family support
- atom bios support (for posting card mostly)
- finish superioctl skeleton
- what else ? :)
Hong Liu
Jakob Bornecrantz
Jerome Glisse
Dave Airlie