Night Light not working on Raspberry Pi 4/400

[robolob]

Hi all,
I just bought a Raspberry Pi 4 4GB and installed Ubuntu 20.10 64bit Desktop.
Night Light doesn't work.
Many people don't even know what that is:
Settings -> Dislplays -> Night Light
I rebooted, deleted .config/dconf, reinstalled Ubuntu: it doesn't work.
Thank you and best wishes for 2021.
Robolob the noob

[Daniel van Vugt (vanvugt)]

Night light depends on a feature called a "gamma ramp". That feature is not supported without at least a proper KMS graphics driver. That should be available for Raspberry Pi 4 in kernel versions 5.10.7 onward, in theory.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Daniel van Vugt (vanvugt)]

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.

[Juerg Haefliger (juergh)]

The HVS on the Pi 4B seems different from the older Pis and color management is therefore disabled in the vc4 driver until that's fixed: https://github.com/torvalds/linux/commit/eb92bc72cdab2550fa1c5b05b866bf209df9fd08

FWIW, it's working on a Pi 3B+.

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1909747