We now have full KMS support (since bug 1918110 was fixed) and Night Light still isn't working.
Comparing the 'drm_info' output between Raspberry Pi 4 and my Intel desktop it looks like the missing feature is the "GAMMA_LUT" related properties on the CRTCs. So this is a feature lacking in the 'vc4' kernel driver.
We now have full KMS support (since bug 1918110 was fixed) and Night Light still isn't working.
Comparing the 'drm_info' output between Raspberry Pi 4 and my Intel desktop it looks like the missing feature is the "GAMMA_LUT" related properties on the CRTCs. So this is a feature lacking in the 'vc4' kernel driver.