Disable KDE monitor brightness control?

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1

After upgrading to Fedora 40 and so Plasma 6 (on Wayland), I was perplexed by my external monitor’s brightness resetting to 100% all the time.

Someone on r/fedora pointed me to the brightness control that is now visible in the tray.

How can I disable this brightness control so that I can still use my monitor’s built-in controls and KDE does not reset them?

EDIT: according to an r/kde discussion I need to set a POWERDEVIL_NO_DDCUTIL=1 environment variable for the PowerDevil service on startup. But how do I set it? I don’t see a “powerdevil” or “PowerDevil” service in the output of “sudo systemctl list-unit-files”

2

i’m also not happy with the brightness control in the system tray under kubuntu 24.10 (X11) .

it only seems to control the brightness of my 2nd monitor and it keeps causing the monitor to dim about 20% on a random basis (whether nite control is on or not).

so i’m constantly having to fiddle with it as my 2nd monitor gets brighter and dimmer at random times.

i would like to keep nite control operational (because it works on both monitors and at predictable times) but i would like this random brightness control thing to stop doing that.

so following this thread to see what my options are.

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3

There has been a lot of brightness work in Plasma 6.2, with some new features to manage multi-screen brightness control, and unfortunately it looks like introduced some unintended behaviors. There are quite a few discussions about this in this forum, here’s a link to one that lists some relevant bug reports that you may want to track.

Regarding how to disable powerdevil DDC control:

  1. Open a terminal (for example, by running Konsole)
  2. Run the command systemctl --user edit plasma-powerdevil.service
  3. In the editor that opens, in the first open section, type:
[Service]
Environment=POWERDEVIL_NO_DDCUTIL=1

then save and exit.
4. Log out and log back in.

If you ever want to revert that, you can run the edit command again and remove those lines, or simply delete the directory ~/.config/systemd/user/plasma-powerdevil.service.d

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4

will that edit affect my ability to control the night light feature from settings/colors & themes/night light?

5

I don’t believe so - the night light feature is using kwin compositor filters and doesn’t actually has anything to do with brightness.

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6

adding the override.conf file worked to remove the slider but the ill effects on my monitor brightness (the dimming) are still present.

tried running the edit command again and deleting those two lines but after closing the editor (nano in my case) i get the following notification on my terminal

after editing, new contents are empty, not writing file.

so i’m now going to try just deleting the whole directory and relogging.

brb

that’s better, restored the slider and adjusted the brightness of the 2nd monitor to be equal to my main and then repeated the procedure.

now my monitor is the right brightness and i have no more slider in the brightness control so hopefully it won’t change again on it’s own.

night light controls are still there and operational.

thanks

7

That did it for me, thanks! The system tray sliders are still present and they still modify the system’s brightness, but they no longer directly control my monitor settings, which is exactly what I wanted.

I was previously trying to modify the powerdevilrc file in ~/.config to no avail; out of all the solutions I’ve seen online, this is the only one that’s worked for me on Fedora 41.

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8

There’s a graphical utility called gddccontrol that you can get easily from your operating system repository that will let you control the monitor brightness manually - and has no interaction with powerdevil so it won’t be affected by Plasma stuff.

You can also get the ddcutil command line tool - which is what I use to setup my display’s brightness after powerdevil messes it up - but it’s pretty complicated to figure out.