Bug 506135

Summary: screen sleep doesn't work on second monitor but works on the first monitor
Product: [Plasma] plasmashell Reporter: jumjo <jumjo132883>
Component: Power management & brightnessAssignee: Plasma Bugs List <plasma-bugs>
Status: RESOLVED FIXED    
Severity: normal CC: jumjo132883, kdedev, nate, xaver.hugl
Priority: NOR Keywords: regression
Version First Reported In: 6.4.0   
Target Milestone: 1.0   
Platform: Other   
OS: Linux   
Latest Commit: https://invent.kde.org/plasma/kwin/-/commit/8f331a268cf1e457b8727080763869e1b426dae8 Version Fixed In: 6.4.3
Sentry Crash Report:
Bug Depends on:    
Bug Blocks: 506459    

Description jumjo 2025-06-25 04:43:32 UTC 
SUMMARY
I set my power management to have my screen dim after 5 min, then turn off the screen after 10 min of no activity. This worked on the previous version of KDE plasma on Fedora 42. As soon as I updated to the new version, the second monitor will consistently turn off with the main monitor and then turn back on. It does this after a fresh boot and with other programs on, and doesn't matter if I have a program on the screen or not. And it is consistently always the second monitor, my main monitor works just fine as far as I have observed this issue as well as before the issue occurred. 

STEPS TO REPRODUCE
1. set dim screen to (x) time and set turn screen off (x) time.
2. Fedora 42 on KDE Plasma 6.4.0
3. 

OBSERVED RESULT
2nd screen turns off then on 
Main screen turns off and stays off until an input is registered


EXPECTED RESULT
both screens stay off until an input is registered 

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.0
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.14.11-300.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 24 × AMD Ryzen 9 5900X 12-Core Processor
Memory: 64 GiB of RAM (62.7 GiB usable)
Graphics Processor: AMD Radeon RX 6900 XT


ADDITIONAL INFORMATION
main screen is 1440p, 144hz , HDR on and the second screen is 1080p 75hz no HDR
Comment 1 TraceyC 2025-07-01 22:27:34 UTC 
I'm not seeing this on git-master

Screens
Laptop 3840 x 2400 @ 150%
2 external monitors 3440 x 1440 @100 % - connected via USB-C dock
Comment 2 Bug Janitor Service 2025-07-03 15:34:05 UTC 
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/7868
Comment 3 Zamundaaa 2025-07-04 13:33:42 UTC 
Git commit e177e1d2da8a278f85d5d3e24ffdc01e7c2eaca6 by Xaver Hugl.
Committed on 04/07/2025 at 13:10.
Pushed by zamundaaa into branch 'master'.

backends/drm: don't use UUID to identify outputs

The UUID is only set later by the output configuration system, so it can't be used in
the drm backend when deciding the dpms state of a "new" output.
This changes it to use EDID ID, EDID hash or connector name instead, which are valid
much earlier and are reliable enough for the dpms workaround.
Related: bug 493879, bug 505953

M  +19   -3    src/backends/drm/drm_backend.cpp

https://invent.kde.org/plasma/kwin/-/commit/e177e1d2da8a278f85d5d3e24ffdc01e7c2eaca6
Comment 4 Zamundaaa 2025-07-04 14:40:01 UTC 
Git commit 8f331a268cf1e457b8727080763869e1b426dae8 by Xaver Hugl, on behalf of Xaver Hugl.
Committed on 04/07/2025 at 13:57.
Pushed by zamundaaa into branch 'Plasma/6.4'.

backends/drm: don't use UUID to identify outputs

The UUID is only set later by the output configuration system, so it can't be used in
the drm backend when deciding the dpms state of a "new" output.
This changes it to use EDID ID, EDID hash or connector name instead, which are valid
much earlier and are reliable enough for the dpms workaround.
Related: bug 493879, bug 505953


(cherry picked from commit e177e1d2da8a278f85d5d3e24ffdc01e7c2eaca6)

Co-authored-by: Xaver Hugl <xaver.hugl@kde.org>

M  +19   -3    src/backends/drm/drm_backend.cpp

https://invent.kde.org/plasma/kwin/-/commit/8f331a268cf1e457b8727080763869e1b426dae8