https://bugs.kde.org/show_bug.cgi?id=435259
Bug ID: 435259
Summary: Screen Resolution changes after screen power saving
mode
Product: systemsettings
Version: 5.21.3
Platform: Archlinux Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: kcm_kscreen
Assignee: kscreen-bugs-n...@kde.org
Reporter: f...@hedgeware.net
CC: plasma-b...@kde.org
Target Milestone: ---
Created attachment 137266
--> https://bugs.kde.org/attachment.cgi?id=137266&action=edit
Shows the available screen resolutions when the bug occurs. Compare with the
list provided by kscreen-doctor.
SUMMARY
Secondary display (Dell P2421DC) connected to the laptop (Dell Latitude 7410)
via USB-C with max resolution of 2560x1440. It normally works, but sometimes
when the screen is going to power saving mode (when not moving the mouse for a
while) and waking up again (e.g. by moving the mouse) to the lock screen the
screen resolution is changed to 1920x1200.
In the screen settings module the maximum listed resolutions are then 1920x1200
and 2048x1080 (see screenshot). Only when unplugging and re-plugging the
screen, the correct resolution (2560x1440) appears again.
However, `kscreen-doctor -o` includes all resolutions:
Output: 69 DP-2 enabled connected DisplayPort Modes: 101:1024x768@60
116:800x600@60 129:640x480@60 2913:2560x1440@60! 2914:1920x1200@60*
2915:2048x1080@60 2916:1920x1080@60 2917:1920x1080@50 2918:1920x1080@60
2919:1920x1080@60 2920:1920x1080@50 2921:1920x1080@60 2922:1600x1200@60
2923:1280x1024@75 2924:1152x864@75 2925:1280x720@60 2926:1280x720@50
2927:1280x720@60 2928:1024x768@75 2929:800x600@75 2930:720x576@50
2931:720x480@60 2932:720x480@60 2933:640x480@75 2934:640x480@60 2935:720x400@70
77:1680x1050@60 84:1280x1024@60 94:1280x800@60 Geometry: 0,0 1920x1200 Scale: 1
Rotation: 1
also `xrandr` reports that the resolution is available:
DP-2 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 527mm x
296mm
2560x1440 59.95 +
1920x1200 59.88*
2048x1080 60.00
1920x1080 60.00 50.00 59.94
1920x1080i 60.00 50.00 59.94
1600x1200 60.00
1680x1050 59.95
1280x1024 75.02 60.02
1280x800 59.81
1152x864 75.00
1280x720 60.00 50.00 59.94
1024x768 75.03 60.00
800x600 75.00 60.32
720x576 50.00
720x480 60.00 59.94
640x480 75.00 60.00 59.94
720x400 70.08
STEPS TO REPRODUCE
1. Connect external screen
2. Wait for system to go to lock screen and then to turn of the external
display
3. Wake up (e.g. by moues movement), lock screen appears in wrong resolution
OBSERVED RESULT
After the secondary screen turns on again, the resolution is changed to
1920x1200. Previous resolution of 2560x1440 cannot be selected from the screen
settings module, although xrandr and kscreen-doctor show that they are
available (the resolution is not part of the drop-down list of available
resolutions)
EXPECTED RESULT
The resolution should not change to 1920x1200 after power savings mode of
secondary screen and resolution of 2560x1440 should always be selectable.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.21.3
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2
Kernel Version: 5.11.10-arch1-1
OS Type: 64-bit
Graphics Platform: X11
Processors: 8 × Intel® Core™ i5-10310U CPU @ 1.70GHz
Memory: 15.3 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics
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