Bug 508006

Summary: Display brightness improperly set after DPMS display cycle on->off->on
Product: [Plasma] kwin Reporter: Christopher Snowhill <kode54>
Component: colour-managementAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: normal CC: holo-doc, xaver.hugl
Priority: NOR    
Version First Reported In: 6.4.4   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Christopher Snowhill 2025-08-08 04:47:59 UTC 
SUMMARY
As of Plasma 6.4.4, when DPMS powers off my Asus ROG Strix XG27UCS, when it powers on again, the monitor is dimmed. Upon unlocking the screen, the desktop screen is severely darkened, except for the brightest colors, which seem to be relatively normal.

STEPS TO REPRODUCE
1. Enable HDR mode
2. Lock the screen
3. Press escape so the screen shuts off
4. Wait for DPMS to activate and power it off completely
5. Press a key to wake the screen
6. Unlock the desktop

OBSERVED RESULT
Screen is darkened. This effect cannot be captured with a screen shot.

EXPECTED RESULT
Screen is not darkened.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux - kernel 6.16.0-5-cachyos (64-bit)
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.16.0 
Qt Version: 6.9.1

ADDITIONAL INFORMATION
The effect goes away if I reset the display color settings, such as by toggling the accuracy/efficiency setting, or by running the HDR tuning wizard.
Comment 1 Zamundaaa 2025-08-11 12:47:52 UTC 
This is a driver bug, see https://gitlab.freedesktop.org/drm/amd/-/issues/4444#note_3032557