My monitor brightness settings vanished. The icon is still on my panel where I left it and still has night light on it, but the brightness settings are gone. Hovering over the icon still says “Scroll to adjust screen brightness” but it doesn’t do anything anymore. I am using Plasma.
This is my first time reporting on anything with this, so if need anything more just let me know. The “Brightness and Color Settings” menu only has Keyboard Shortcuts and About now. Nothing else.
This happens for me as well on stable, but usually only after hibernation or sleep. I was hoping this was fixed in a more recent version of Plasma, but it seems not.
You can try to manually restart the powerdevil service
systemctl --user restart plasma-powerdevil.service
That fixes it for me until the next time my computer goes to sleep.
Tried that, didn’t fix it for me. I don’t put my computer into hibernation or sleep, it just basically runs 24/7 until I decide to restart it, or after a test update. After this update is the first time after roughly a month of working fine that it just vanished on me.
Thank you, though. I had tried searching for it but came up empty. Could just be an issue with me lol
ok, I just checked. The brightness and control window is still empty for me as well, but when I move the mouse over the brightness icon, I can then make the display brighter or dim it using the scroll wheel.
I’m on Plasma Wayland and scrolling the mouse wheel over the brightness icon is doing nothing at all. Tested with the Night Light active & suspended - no change.
No brightness setting appears on the popup when the system tray icon is clicked.
BTW, I’m back on kernel 6.12, so it is not an issue related to the 6.13RC I mentioned I had installed earlier in this topic. And I am running tuned-ppd instead of power-profiles-daemon, although I don’t think that is the cause of the brightness issue.
The scroll wheel brightness worked for me before this update. But yea, even with the fix he listed above that didn’t fix that part for me either. And I am on X11 and 6.12 kernel. Night light is the only thing that still works fine.
I know this isn’t a huge issue, but still a setting that was pretty useful for me since my monitor controls are on the back of the monitor and not easily accessible, is only reason I brought it up.
Are we talking Plasma 6.2.4 for brightness via wheel or Cinnamon 6.4?
@grau’s profile indicates they are on Plasma, and I’m on Plasma 6.2.4, so it looks like the adjusting brightness with the scroll wheel is a Plasma 6.2.4 issue.
It works just fine for me. Also Plasma/Wayland 6.2.4, 6.12.1.-4, tuned-ppd. Radeon, btw. There is a lag before it dims or brightens, but it does work, as does the fly-out window.
I just did a full shutdown & power-off at the power point this time. Rebooted, and adjusting brightness with the scroll wheel is working again.
I’ll keep an eye on it - maybe the problem is gone, or maybe it only happens after my mini-PC is woken from sleep.
That could be. I’ve never trusted sleep, hibernate, etc. It’s a 1/0 thing for me. No quantum fuzz.
As predicted, after waking my mini-PC from sleep, I was again unable to adjust the brightness by scrolling the mouse wheel over the Plasma brightness/night-light system tray icon.
A bit of searching the web found a solution in this Reddit thread:
• 2mo ago •
If yours ever disappears again you can bring it back with
systemctl --user restart plasma-powerdevil.service
I can confirm that restarting the plasma-powerdevil.service fixed the issue for me.
no need to go searching on reddit. Simply scrolling up a little bit would have helped as well 
Just quoting my original post because after reading replies I noticed I failed to really mention the entire issue on my end. Yes, the scroll wheel to control brightness doesn’t work (none of the fixes in this thread fixed for me), but the sliders to control brightness are also gone. Anything to do with controlling the brightness levels of both my monitors are just straight up gone.
I am starting to think that the Plasma brightness issue is not related to suspend, but rather to the screen switching off after a period of inactivity. The last thing I did on my mini-PC last night was manually suspend it to sleep mode via Plasma’s menu.
When I resumed my PC this morning, the brightness controls were as they should be, with the mouse wheel able to adjust screen brightness, and the brightness slider showing in the system tray popup. So I don’t think suspend is the issue.
However, after my screen was turned off due to inactivity an hour or so later I found that the issue had reoccurred and I had to manually restart the plasma-powerdevil.service again. I have Plasma’s Power Management set to turn my screen off after 8 minutes and put my system to sleep after 15 minutes.
Anyway, it looks like the issue occurs at 10:50am (that must be when I moved the mouse to wake the screen up). There are 3 failed attempts to open the display and set the brightness before the following message:
org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 failed to set DDC/CI brightness
I think that is when the ability to adjust brightness via the system tray icon disappears.
Here’s a more complete copy & paste from my system log (sorry for the formatting - it is from the GUI app). I manually restarted Powerdevil at 11:04am.
|30/11/24 9:26 am|org_kde_powerdevil|qt.qpa.wayland: Creating a fake screen in order for Qt not to crash|
|---|---|---|
|30/11/24 9:26 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3029|
|30/11/24 9:26 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 retrying to set DDC/CI brightness in 1000 milliseconds - attempt no. 1|
|30/11/24 9:26 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_get_non_table_vcp_value -3007|
|30/11/24 9:26 am|org_kde_powerdevil|dh=Display_Handle[i2c-1: fd=33], Keeping adjusted sleep multiplier 2.00 for SE_POST_WRITE or SE_POST_SAVE_SETTINGS|
|30/11/24 10:50 am|org_kde_powerdevil|qt.qpa.wayland: Creating a fake screen in order for Qt not to crash|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3030|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 retrying to set DDC/CI brightness in 1000 milliseconds - attempt no. 1|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3030|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 retrying to set DDC/CI brightness in 2000 milliseconds - attempt no. 2|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3030|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 retrying to set DDC/CI brightness in 3000 milliseconds - attempt no. 3|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3030|
|30/11/24 10:50 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDisplay]: PHL 243V7 failed to set DDC/CI brightness|
|30/11/24 10:50 am|org_kde_powerdevil|qt.qpa.wayland: Creating a fake screen in order for Qt not to crash|
|30/11/24 11:04 am|systemd|Stopping Powerdevil...|
|30/11/24 11:04 am|systemd|Stopped Powerdevil.|
|30/11/24 11:04 am|systemd|plasma-powerdevil.service: Consumed 1.208s CPU time, 19.8M memory peak.|
|30/11/24 11:04 am|systemd|Starting Powerdevil...|
|30/11/24 11:04 am|org_kde_powerdevil|Initializing libddcutil. ddcutil version: 2.1.4, shared library: /usr/lib/libddcutil.so.5.1.2|
|30/11/24 11:04 am|org_kde_powerdevil|Options passed from client:|
|30/11/24 11:04 am|org_kde_powerdevil|Applying combined options:|
|30/11/24 11:04 am|org_kde_powerdevil|Library initialization complete.|
|30/11/24 11:04 am|org_kde_powerdevil|org.kde.powerdevil: [DDCutilDetector]: Failed to initialize callback|
|30/11/24 11:04 am|systemd|Started dbus-:1.2-org.kde.powerdevil.discretegpuhelper@2.service.|
|30/11/24 11:04 am|systemd|Started dbus-:1.2-org.kde.powerdevil.chargethresholdhelper@2.service.|
|30/11/24 11:04 am|systemd|Started dbus-:1.2-org.kde.powerdevil.backlighthelper@2.service.|
|30/11/24 11:04 am|backlighthelper|org.kde.powerdevil: no kernel backlight interface found|
|30/11/24 11:04 am|org_kde_powerdevil|org.kde.powerdevil: org.kde.powerdevil.chargethresholdhelper.getthreshold failed Charge thresholds are not supported by the kernel for this hardware|
|30/11/24 11:04 am|org_kde_powerdevil|org.kde.powerdevil: org.kde.powerdevil.backlighthelper.brightness failed|
|30/11/24 11:04 am|systemd|Started Powerdevil.|
|30/11/24 11:04 am|org_kde_powerdevil|org.kde.powerdevil: Handle button events action could not check for screen configuration|
|30/11/24 11:04 am|org_kde_powerdevil|org.kde.powerdevil: org.kde.powerdevil.chargethresholdhelper.getthreshold failed Charge thresholds are not supported by the kernel for this hardware|
|30/11/24 11:04 am|systemd|dbus-:1.2-org.kde.powerdevil.chargethresholdhelper@2.service: Deactivated successfully.|
|30/11/24 11:04 am|systemd|dbus-:1.2-org.kde.powerdevil.backlighthelper@2.service: Deactivated successfully.|
|30/11/24 11:04 am|systemd|dbus-:1.2-org.kde.powerdevil.discretegpuhelper@2.service: Deactivated successfully.|
I wish I even had this much to show. I don’t have any errors because all the Brightness settings were just completely gone after rebooting from this update for me. My screens are set to never turn off unless I manually shut them off when I go to bed or leave the house.
Starting to just think this is an issue on my end somehow since you guys are all able to get the brightness sliders and everything back just fine. I just have a blank menu. I ain’t gonna worry about it anymore, I think I have spammed this section enough lol
Maybe check the output of:
systemctl --user status plasma-powerdevil.service
It should be similar to this:
systemctl --user status plasma-powerdevil.service ✔ 17s
● plasma-powerdevil.service - Powerdevil
Loaded: loaded (/usr/lib/systemd/user/plasma-powerdevil.service; static)
Active: active (running) since Sat 2024-11-30 11:04:11 AEDT; 1h 27min ago
Invocation: 00804ba44c65457ab439f5b454fb286c
Main PID: 1120016 (org_kde_powerde)
Tasks: 14 (limit: 34653)
Memory: 16.2M (peak: 19.9M)
CPU: 524ms
CGroup: /user.slice/user-1000.slice/user@1000.service/background.slice/plasma-powerdevil.service
└─1120016 /usr/lib/org_kde_powerdevil
You may also see some lines below that output showing logged errors/warnings/info.
Thank you. I just get this:
plasma-powerdevil.service - Powerdevil
Loaded: loaded (/usr/lib/systemd/user/plasma-powerdevil.service; static)
Active: active (running) since Thu 2024-11-28 07:52:28 CST; 1 day 12h ago
Invocation: 09dc87e47d4546719952c1c14c93ce1e
Main PID: 38370 (org_kde_powerde)
Tasks: 6 (limit: 38057)
Memory: 17.4M (peak: 19.4M)
CPU: 6.995s
CGroup: /user.slice/user-1000.slice/user@1000.service/background.slice/plasma-powerdevil.service
└─38370 /usr/lib/org_kde_powerdevil
Nov 28 22:43:41 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:41 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Nov 28 22:43:42 OkerlundPC org_kde_powerdevil[38370]: org.kde.powerdevil: Adjust screen brightness step failed: no displays available to adjust
Guess that explains why there are no settings, it no longer detects my monitors.
That shows the plasma-powerdevil.service has not been restarted since then.
Try restarting the service again:
systemctl --user restart plasma-powerdevil.service
Ensure you don’t use sudo for that command.
Then see if the brightness controls return. If they don’t, run the
systemctl --user status plasma-powerdevil.service
command again to see what the log shows after the service was restarted.
Now I just get failed messages.
Nov 29 20:40:58 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3021
Nov 29 20:40:58 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: "VG27A" retrying to initialize DDC/CI brightness in 200>
Nov 29 20:41:00 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3021
Nov 29 20:41:00 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: "VG32VQ1B" retrying to initialize DDC/CI brightness in >
Nov 29 20:41:00 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3021
Nov 29 20:41:00 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: "VG27A" retrying to initialize DDC/CI brightness in 300>
Nov 29 20:41:03 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3021
Nov 29 20:41:03 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: "VG32VQ1B" failed to initialize DDC/CI brightness
Nov 29 20:41:03 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: ddca_open_display2 -3021
Nov 29 20:41:03 OkerlundPC org_kde_powerdevil[152448]: org.kde.powerdevil: [DDCutilDisplay]: "VG27A" failed to initialize DDC/CI brightness