Bug 500997

Summary:	The percentage of brightness slider does not sync with OSD settings on monitor that remembers per-mode brightness levels
Product:	[Plasma] plasmashell	Reporter:	BryanLiang <liangrui.ch>
Component:	Brightness and Color widget	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	REPORTED ---
Severity:	minor	CC:	natalie_clarius, nate, thomas.agnola
Priority:	NOR
Version First Reported In:	6.3.2
Target Milestone:	1.0
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Visual presentation of mismatched brigthness value

Description BryanLiang 2025-03-03 10:27:10 UTC

SUMMARY
The percentage of brightness slider does not sync with OSD settings.

There are few modes in my monitor OSD settings like normal, low-blue. Each mode has its own brightness. When I switch one mode to another, the percentage of brightness slider in panel widget is not synced with that.


STEPS TO REPRODUCE
Here is the screen record of the situation: https://youtu.be/S8n0m8F9iJI

OBSERVED RESULT
The brightness slider does not sync with OSD settings.

EXPECTED RESULT
The percentage of brightness slider is same as OSD settings

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.3.2
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.6.72-x64v3-xanmod1-1-lts (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800H with Radeon Graphics
Memory: 13.5 GiB of RAM
Graphics Processor: AMD Radeon Graphics

ADDITIONAL INFORMATION

Comment 1 Nate Graham 2025-03-05 16:37:38 UTC

Possibly a DDC issue for not sending change events? Or possibly our issue for not listening to or reacting to them, if it does send them. Needs someone with relevant knowledge and hardware to investigate.

Comment 2 BryanLiang 2025-03-10 13:25:00 UTC

I found a similar bug report: https://bugs.kde.org/show_bug.cgi?id=470106. But if so, the bug should have been fixed.

Comment 3 Thomas AGNOLA 2025-11-01 14:47:04 UTC

Similar problem on a DELL P2723DE.
Was set to 25% brightness on OSD but KDE see it at 100%.
I can change the OSD value from Linux with ddcui that report the correct brightness value.
The screen is connected via HDMI.

SOFTWARE/OS VERSIONS
Operating System: Kubuntu 25.10
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.2
Kernel Version: 6.17.0-6-generic (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800H with Radeon Graphics
Memory:  32 GiB of RAM
Graphics Processor 1 : AMD Radeon Graphics
Graphics Processor 2 : NVIDIA GeForce RTX 3070 Laptop GPU

Comment 4 Thomas AGNOLA 2025-11-01 14:48:56 UTC

Created attachment 186388 [details]
Visual presentation of mismatched brigthness value