Bug 492421 - Brightness slider locked at 21%
Summary: Brightness slider locked at 21%
Status: RESOLVED FIXED
Alias: None
Product: plasmashell
Classification: Plasma
Component: Power management & brightness (show other bugs)
Version: 6.2.4
Platform: Other Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2024-08-30 19:27 UTC by steve
Modified: 2025-02-24 17:46 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed In: 6.3.0
Sentry Crash Report:


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Description steve 2024-08-30 19:27:12 UTC
***
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***

SUMMARY
Display Brightness stops being adjustable.

STEPS TO REPRODUCE
1. Click on widget
2. Attempt to adjust slider
3. 

OBSERVED RESULT
Brightness level locked at 21%

EXPECTED RESULT
Brightness would adjust with slider movement

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: Arcolinux, linux kernel: 6.10.6-arch1-1
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Not exactly sure when this behavior began but 2-3 weeks ago, and it may be intermittent. Have tried disabling Night Light to no effect.
Comment 1 paninomaninodesu 2024-08-31 13:56:01 UTC
Can you give more information?
How you try to adjust the brightness, exactly?
Using the mouse wheel? Dragging the slider with the mouse? Do you use function keys on notebook or a keyboard shortcut?
Is just the slider that is stuck but NOT the screen brightness? The screen still goes beyond the value that the interface is stuck?

Would be helpful if you could record a short video showing your attempts.
Comment 2 steve 2024-08-31 18:46:28 UTC
(In reply to paninomaninodesu from comment #1)
> Can you give more information?
> How you try to adjust the brightness, exactly?
> Using the mouse wheel? Dragging the slider with the mouse? Do you use
> function keys on notebook or a keyboard shortcut?
> Is just the slider that is stuck but NOT the screen brightness? The screen
> still goes beyond the value that the interface is stuck?
> 
> Would be helpful if you could record a short video showing your attempts.

In the widget I use the mouse to click and hold/drag the slider button. It moves the button but it pops back immediately. The brightness doesn't change despite the the button being stuck.
Also, this appears to be intermittent, and it is currently working. I have upgraded the system once, which included a kernel upgrade. I also manually set the location for nightlight as it looked like it wasn't able to determine location through wifi. Next time it happens I'll post a vid.
Comment 3 paninomaninodesu 2024-09-01 18:58:14 UTC
(In reply to steve from comment #2)
> In the widget I use the mouse to click and hold/drag the slider button. It
> moves the button but it pops back immediately. The brightness doesn't change
> despite the the button being stuck.
> Also, this appears to be intermittent, and it is currently working. I have
> upgraded the system once, which included a kernel upgrade. I also manually
> set the location for nightlight as it looked like it wasn't able to
> determine location through wifi. Next time it happens I'll post a vid.

Consider started the system selecting an older kernel.
Current Kernel 6.8 for Neon has a problem that makes the screen blinks randomly. It's scary, looks like the screen is on the vergo and breaking up. So I'm using the advanced options during booting to select Kernel 6.5, maybe, just maybe, there's some "bug" in the current Kernel you're using that is causing this problem.
I may be talking nonsense, but is who knows?
If you have the time, some day keep restarting changing Kernels and switching from X11 and Wayland to see if you notice something.
Comment 4 steve 2024-09-02 01:59:38 UTC
It started working again after a restart. Then it just stopped again but I am not thinking that it is entirely related to something with Nightlight because it seems to happen when it activates. I disabled Nightlight, no effect, so rebooted and now it works. I turned Nighlight back on and it continues to work. Additionally, I've noticed that Nightlight is no longer finding my location automatically, so I need to set it manually.
Comment 5 steve 2024-09-02 02:00:57 UTC
Sorry, I AM thinking it is related to Nightlight.
Comment 6 steve 2024-09-02 02:22:59 UTC
(In reply to steve from comment #5)
> Sorry, I AM thinking it is related to Nightlight.

After a few minutes of turning it back on, the slider sticks again and the value it was set. Disabling Nightlight has no effect. Restarting.
Comment 7 steve 2024-09-02 02:23:37 UTC
(In reply to steve from comment #4)
> It started working again after a restart. Then it just stopped again but I
> am thinking that it is entirely related to something with Nightlight
> because it seems to happen when it activates. I disabled Nightlight, no
> effect, so rebooted and now it works. I turned Nighlight back on and it
> continues to work. Additionally, I've noticed that Nightlight is no longer
> finding my location automatically, so I need to set it manually.
Comment 8 steve 2024-09-02 02:26:10 UTC
(In reply to steve from comment #6)
> (In reply to steve from comment #5)
> > Sorry, I AM thinking it is related to Nightlight.
> 
> After a few minutes of turning it back on, the slider sticks again and the
> value it was set. Disabling Nightlight has no effect. Restarting.

Restart fixed it.
Comment 9 paninomaninodesu 2024-09-03 13:29:12 UTC
(In reply to steve from comment #8)
> (In reply to steve from comment #6)
> > (In reply to steve from comment #5)
> > > Sorry, I AM thinking it is related to Nightlight.
> > 
> > After a few minutes of turning it back on, the slider sticks again and the
> > value it was set. Disabling Nightlight has no effect. Restarting.
> 
> Restart fixed it.

"Restart fixed it."

By restart you mean reboot? Logoff?
Here I have a Ctrl+F6 setup as a shortcut to refresh Plasma (kquitapp5 plasmashell && kstart5 plasmashell).
Sometimes this is enough.
Comment 10 steve 2024-09-03 20:52:09 UTC
Sorry, systemctl reboot. I disabled Nightlight also, and the problem hasn't reoccurred.
Comment 11 Jakob Petsovits 2025-02-24 17:46:11 UTC
Plasma 6.3.0 had a bunch of fixes to keep the brightness applet in sync with the current state of displays, and I believe it won't get stuck like this anymore. Feel free to reopen the bug if you happen to run into this again on 6.3 or later.