r600 tearfree video on Linux, it is a reality

For some reason I always read "tear" as in crying. I understand that tearing can make some people cry so maybe I am not that far off. Anyway, I got the latest git of drm-radeon-testing, libdrm, mesa and xf86-video-ati. After installing all that everything seems to be running really nicely. I can drag an gnome-mplayer window around the screen and the video does not exhibit any tearing. Even large windows like a browser look good. The only tearing I do get is when I drag a window from one display to another in my dual head setup. I talked to agd5f on #radeon and he said that was due to different pixel clocks on the two displays. He said it could be fixed in software, however. I said while it would be nice to have fixed. I'm sure there are more important things to deal with first.