none of the 3d drivers
support suspend/resume.

I wish I'd found this email long ago.
> after a software suspend/resume cycle, running glxgears emits the following error msgs and quits:
With the semi-exception of the radeon driver, none of the 3d drivers support suspend/resume.

I was about to start digging and playing with the kernel code, I even started to unload/reload the DRI/DRM modules after resuming.
Now I know it's not a specific problem to me, And I've reverted back to using APM.