So Pierre Ossman took my previous vline anti-tearing patches and saw them through. We now have mostly tear free rendering in the radeon driver if you want it! For textured video it’s on by default, but you can disable it by toggling the XV_VSYNC Xv attribute. For EXA, you can enable the EXAVSync option in your xorg.conf if you want to play with tear free desktop rendering, however, since it works by stalling the CP until the display controller has passed the destination region in the front buffer, it’s a trade off performance-wise. The crtc selection for dualhead could use some optimization, but it should work well in most cases.
As an added bonus, Pierre fixed Maciej and Corbin’s bicubic Xv filtering for r3xx/r4xx and that has been merged as well.
Thanks to all involved!