gamma curve update not applied if output is in DPMS off state
We are seeing reports in GNOME (wayland) that Nightlight (which adjust the gamma curve during night time) does not turn off in the morning. Trying to reproduce it, the problem appears to be that gamma curve updates are lost when the monitors are turned off (DPMS off).
We could probably easily work around this by re-applying the gamma curve in mutter when we turn the monitors back on. But it could also be considered an i915 bug and the gamma curve updates should still be correctly applied.
See https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/issues/549