https://bugs.freedesktop.org/show_bug.cgi?id=107928
--- Comment #15 from Vik-T viktor@troja.ch --- Someone might find this helpful: I managed to reduce the number of driver crashes considerably by disabling "suspend" and "off" mode in X.
Section "ServerFlags" Option "SuspendTime" "0" Option "OffTime" "0" EndSection
In the last 5-6 days, the driver crashed only once and I managed to bring X back without rebooting. For me, that's a huge improvement over the situation before where I had to reboot 2-3 times a day.