But I can't revert commit 6f94569 on top of HEAD.

During some restarts I got this in dmesg:
[    4.159787] [drm:btc_dpm_set_power_state [radeon]] *ERROR*
rv770_restrict_performance_levels_before_switch failed

And my reported
r600 - NI/Turks: flickering with 'geom-outlining-150'
seems to be related!?

It was first gone under drm-next-4.1-wip but arise with going bak to
drm-next-3.20-wip (3.19-rc5). I had to power down my system to get it back
after 'git bisect reset' and got the above messages during some power cycles.