[Bug 73067] RV770 - screen flicker with radeon.dpm=1

https://bugs.freedesktop.org/show_bug.cgi?id=73067

--- Comment #10 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #9)

Yes, the attached patch fixed the flicker. Screen does not flick whichever value is power_dpm_state or power_dpm_force_performance_level.

Before the patch, the flicker happened when switching from power level 2 sclk: 66500 mclk: 95000 vddc: 1082 to power level 1 sclk: 50000 mclk: 70000 vddc: 1046

In the way level 1 -> level 2 there is not screen flicker.

The flicker is caused by the mclk transition. It some cases it seems to take longer than the vblank period which is why you are seeing the flicker.