https://bugzilla.kernel.org/show_bug.cgi?id=198123
--- Comment #24 from Michel Dänzer (michel@daenzer.net) --- The radeon driver already calls load_lut when the CRTC dpms hook is called with DRM_MODE_DPMS_ON. Does the ast patch call load_lut even when DPMS is already on? If so, I wonder if it doesn't just paper over the real issue, which is that something changes the LUT but then doesn't call load_lut.