https://bugs.freedesktop.org/show_bug.cgi?id=28771
--- Comment #22 from Andy Furniss lists@andyfurniss.entadsl.com 2010-08-16 02:45:45 PDT --- (In reply to comment #21)
Is there any way currently to just make it swap buffers without regard for my screens vertical retrace? I realise that means I get a lot of tearing but I'd rather have that than a frame rate jumping around like that.
For your chip you have to patch xf86-video-ati + disable as above. I'll attach the patch which someone posted in another bug when I find it.
I think this is going to come up again and again, so I hope in the absence of any way to change it on the fly, that it does get made into an xorg.conf option as suggested in comment 17.