Comment 37 for bug 303697

I don't know if this helps with your tearing, but this seemed to fix my issues on my machine with video problems. I checked to fix the permissions of "/dev/dri/card0", but that did not exist per some other recommendations. I then did a search for "card0" and saw that it existed in "/dev/ati/card0". I changed permissions by adding the ability for the group to use it (g+rw) and made confirmed that I was part of the video group. It seemed to improve my video handling on my machine. Of course your bug is independent of Compiz, but thought this may help others just in case.