Wayland + HDR results in dimmed screens after screen wake-up

[oshunluvr]

I've been trying enabling HDR off and on for the last few months. Color washout was horrible for quite awhile, but now it seems fixed. I re-enabled HDR a couple weeks ago but have not been able to get the screen brightness to a comfortable level. It was super annoying to see the bright SDDM log in screen only to have my screens dim so much after log in that I had to turn off the room lights and squint a bit. I was just hanging on thinking there would be a fix, but nothing yet. Then, I discovered I was a dummy when I finally saw the screen brightness controls in the system tray added by a some update in the past. Hurray! I can see my screens in daylight again!

However, it appears when my screens go into power saving mode due to non-use, they restore to - maybe random - low levels. After setting both screens at 30% and returning awhile later, screen 1 restored at 1% and screen 2 to 3%. This yesterday, screen 2 stayed at 30% but screen one was at 5%.

I can find no entry in Systems Settings to set a default brightness - only "Night Light" screen temps. Alternately, just having it restore to the previous setting would be even better.

Today, after some web searching, I added "POWERDEVIL_NO_DDCUTIL=1" to my profile to see if this helps. I will report on it's success or failure.

[claydoh]

I just added a second monitor to my system over the weekend, a very very cheap and basic LG 24" (~60 USD) model to go alongside my very very cheap Chinese brand (Dahua) 27"
No HDR or any real features on either, The new screen regularly resets itself to 3% brightness.
The tray controls for brightness have never worked for me on the desktop, fwiw.

I will try the tweak you found, and report anything I might find for other remedies, if I find any.


I added the setting to the systemd service, and restarted it.
My tray sliders work now..........on the LG monitor.
(EDIT: Changing the Dahua's settings and turning off "dcr" allowed the tray slider to work there)

systemctl --user edit plasma-powerdevil

Add :

[Service]
Environment="POWERDEVIL_NO_DDCUTIL=1"​

And restart the service

systemctl --user restart plasma-powerdevil

[claydoh]

Ok, this is odd. Maybe my above test can be discarded.
In any case, doing it via the systemd service can be a useful way to test without needing to log out. reboot, etc.

Disabling the setting change and restarting the service does not stop the sliders from working, so....maybe they were working all along?
I haven't rebooted or logged out, so there is that to consider. But my LG most definitely was not responding to the tray slider, and now it is

Anyhow, I'd scratch my head some more, but I don't really want to increase my baldness.