https://bugs.kde.org/show_bug.cgi?id=431856
Bug ID: 431856
Summary: kscreen frequently mess resolution on a dual monitor
setup
Product: KScreen
Version: 5.19.5
Platform: Kubuntu Packages
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: common
Assignee: kscreen-bugs-n...@kde.org
Reporter: luis.henriq...@gmail.com
Target Milestone: ---
SUMMARY
The bug is very frequent but is difficult to reproduce at will. I have a dual
monitor setup. The left monitor is a Dell E198WFP and the left one is a BenQ
XL2420T. The BenQ is connect using a display port and Dell using DVI
When the BenQ returns from sleep or on system boot, kscreen changes the
resolution to 720p on the Benq (right monitor). When this happens this is the
maximum resolution available on the System Settings->Display Configuration.
The refresh rate of the right monitor is also frequently detected incorrectly
and downgraded to 60hz even if the resolution does not change. The correct
maximum refresh rate of this monitor is 120Hz, but is very common to list only
100Hz.
To fix this, I change the positions of the monitors and/or switch off/on the
right monitor until 1920x1080 is available to select. When this happens maximum
refresh rate available is only 60Hz, but it better than nothing.
This bug doesn't happen on Gnome or XFCE.
STEPS TO REPRODUCE
It happens on boot or after the monitor returns from sleep.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu Studio 20.10
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.14.2
ADDITIONAL INFORMATION
kscreen-console bug output:
https://pastebin.com/xbLnt0yV
xrand output from the BenQ monitor (only the 1920x1080 lines):
Screen 0: minimum 320 x 200, current 3360 x 1080, maximum 16384 x 16384
DisplayPort-2 connected primary 1920x1080+1440+0 (0x734) normal (normal left
inverted right 1920x1080 (0x733) 148.500MHz +HSync +VSync +preferred
h: width 1920 start 2008 end 2052 total 2200 skew 0 clock 67.50KHz
v: height 1080 start 1084 end 1089 total 1125 clock 60.00Hz
1920x1080 (0x734) 235.500MHz -HSync -VSync *current
h: width 1920 start 1968 end 2000 total 2080 skew 0 clock 113.22KHz
v: height 1080 start 1083 end 1088 total 1133 clock 99.93Hz
1920x1080 (0x735) 148.500MHz +HSync +VSync
h: width 1920 start 2448 end 2492 total 2640 skew 0 clock 56.25KHz
v: height 1080 start 1084 end 1089 total 1125 clock 50.00Hz
1920x1080 (0x736) 148.352MHz +HSync +VSync
h: width 1920 start 2008 end 2052 total 2200 skew 0 clock 67.43KHz
v: height 1080 start 1084 end 1089 total 1125 clock 59.94Hz
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