https://bugs.freedesktop.org/show_bug.cgi?id=79806
--- Comment #4 from Gabor Enyedi enyecz@gmail.com --- (In reply to comment #3)
Workaround: when resume, execute "echo auto > /sys/class/drm/card0/device/power_dpm_force_performance_level".
How did you do that? It gives me "echo: write error: Invalid argument" on kernel 3.15
It simply works without any trick. It also works with stock kernel 3.13. Are you sure that you have the same ATI card?
What I have found since I have posted the bug is that sometimes (very rarely) this simple workaround is not enough. Now, I use the following:
echo low > /sys/class/drm/card0/device/power_dpm_force_performance_level echo battery > /sys/class/drm/card0/device/power_dpm_state echo auto > /sys/class/drm/card0/device/power_dpm_force_performance_level echo balanced > /sys/class/drm/card0/device/power_dpm_state