Comment 30 for bug 765813

(In reply to comment #10)
> Fyi, my flickering problem got fixed by recompiling mesa. According to Jesse
> Barnes, inconsisten versions of the dri2 and gl proto headers when compiling
> the x server and mesa may lead to this flickering (for unknown reasons).

Last update of dri2 and gl proto headers on my system was before 2010-11-07 (date of my last comment).
I brought my system up-to-date yesterday, and the problem was completely gone.
I went back to older versions of kernel / libdrm / ddx / mesa, and never managed to reproduce the problem.
I did not try to downgrade everything though, there were probably a bunch of other xorg components that were updated by my distrib in the meantime.

vblank was definitely on since fps was either 30 or 60 fps, but no flickering to be seen. Well good news I guess !