Bug 503258

Summary:	Screen brightness increases (15% -> 64%) when logging into a Wayland session after being in an X11 session
Product:	[Plasma] plasmashell	Reporter:	Alexander Potashev <aspotashev>
Component:	Power management & brightness	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	REPORTED ---
Severity:	minor	CC:	kdedev, nate
Priority:	NOR
Version First Reported In:	6.3.4
Target Milestone:	1.0
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Alexander Potashev 2025-04-24 00:03:46 UTC

SUMMARY
Screen brightness increases (15% -> 64%) after Plasma Wayland login.

STEPS TO REPRODUCE
1. Use Plasma X11 session. Set screen brightness (e.g. 15%) using physical buttons on the monitor.
2. Logout.
3. Change to Plasma Wayland in sddm UI.
4. Login.

OBSERVED RESULT
Brightness goes up, to something around 64%. There's no confirmation dialog or notification about brightness change.

EXPECTED RESULT
Brightness shouldn't change without my consent.

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 41
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.2
Kernel Version: 6.13.11-200.fc41.x86_64 (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz
Memory: 15.4 ГиБ of RAM
Graphics Processor 1: Intel® HD Graphics 530
Graphics Processor 2: NVIDIA GeForce GTX 960M

ADDITIONAL INFORMATION

Comment 1 Nate Graham 2025-04-24 08:39:05 UTC

Does it also happen on Wayland?

Comment 2 Alexander Potashev 2025-04-24 21:04:22 UTC

> Does it also happen on Wayland?

What do you mean "on Wayland"? Can you describe a scenario you think deserves testing?

Note that "STEPS TO REPRODUCE" involve both X11 and Wayland.

Comment 3 Nate Graham 2025-04-25 13:41:24 UTC

Sorry, I was reading too fast.

Comment 4 TraceyC 2025-09-24 19:06:52 UTC

I'm not able to reproduce this on git-master with a laptop and external monitor
After following the steps to reproduce, the external monitor retained the same brightness level

Are you still able to reproduce this with Plasma 6.4.5 or later and ddcutil 2.2.1 or later?

Note: The login screen when logging out and back in is the lock screen, not SDDM (which is used for first login after the system starts)

Comment 5 Bug Janitor Service 2025-10-09 03:46:55 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 6 Bug Janitor Service 2025-10-24 03:47:25 UTC

🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.

Comment 7 Alexander Potashev 2025-10-25 21:21:06 UTC

Still reproducible on Plasma Wayland logout/login cycle:
1. Use Plasma Wayland session. Set screen brightness to 50% using physical buttons on the monitor.
2. Logout.
3. Login into a Plasma Wayland session again.
4. Using physical buttons on the monitor to see brightness, it's set to 63%.

Comment 8 Alexander Potashev 2025-10-25 21:21:48 UTC

Re: comment #7

relevant kinfo:

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.19.0
Qt Version: 6.9.2
Kernel Version: 6.17.4-200.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz
Memory: 16 ГиБ of RAM (15.4 ГиБ usable)
Graphics Processor 1: Intel® HD Graphics 530
Graphics Processor 2: NVIDIA GeForce GTX 960M

Comment 9 Alexander Potashev 2025-10-25 21:22:44 UTC

```
$ ddcutil --version 
ddcutil 2.2.1
...
```