When atomically setting gamma ramps on AMDGPU (specifically ), the changes
don't take effect until switching to another TTY and back again. Using the
legacy DRM interface works as expected.

To reproduce, build and run the rootston Wayland compositor:

https://github.com/swaywm/wlroots

We will shortly be merging this patch for a new gamma control protocol
extension, which you will need to apply if we haven't merged it by the time you
attempt it:

https://github.com/swaywm/wlroots/pull/1157

An sample program will be available in the build directory,
./examples/gamma-control, which can adjust gamma. By default this will use the
atomic interface, set WLR_DRM_NO_ATOMIC=1 before starting rootston to use the
legacy interface. Our atomic gamma code is here:

https://github.com/swaywm/wlroots/blob/master/backend/drm/atomic.c#L199-L230