https://bugs.kde.org/show_bug.cgi?id=516631
Bug ID: 516631
Summary: External DP monitor brightness dims to 30% after sleep
and wakeup
Classification: Plasma
Product: plasmashell
Version First 6.6.0
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Power management & brightness
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: 1.0
SUMMARY
External DP monitor brightness dims to 30% after sleep and wakeup.
STEPS TO REPRODUCE
1. Wait for the system to automatically go to sleep when there is no activity.
2. Wakeup the system
3. The brightness is dims to 30%
OBSERVED RESULT
After wakeup, open the monitor's OSD, can see the brightness is set to 30%.
But in System Settings -> Display and monitor, the DDC/CI control bar says the
current brightness is 100%, and adjust this scroll bar is actuallly control the
brightness between 0% to 30% supported maximum brightness of this monitor.
EXPECTED RESULT
The brightness should set back to original, and the DDC/CI control scroll bar
should be able to set the brightness to actual brightness percent.
SOFTWARE/OS VERSIONS
OS: Arch Linux x86_64
KDE Plasma Version: 6.6.0
KDE Frameworks Version: 6.23.0
Qt Version: 6.10.2
ADDITIONAL INFORMATION
I have a dual screen system. Both support DDC/CI, and both will reduce
brightness to 30% after waking up.
The ddcutil is work fine to detect the actual maximum brightness:
```
$ ddcutil -d 2 getvcp 10
VCP code 0x10 (Brightness ): current value = 30, max
value = 100
```
Because the max value of scroll bar for DDC/CI in System Settings is dims to
30% actual, when I tried to set brightness by ddcutil, the ddcutil works fine,
brightness becomes 100%.
```
$ ddcutil -d 2 setvcp 10 100 && ddcutil -d 2 getvcp 10
VCP code 0x10 (Brightness ): current value = 100, max
value = 100
```
After that, control the scroll bar in System Settings, e.g. 50%, it change the
brightness to 15%(30%*50%):
```
$ ddcutil -d 2 getvcp 10
VCP code 0x10 (Brightness ): current value = 15, max
value = 100
```
Then I tried to change brightness to 100 by ddcutil, and restart the
Powerdevil:
```
$ ddcutil -d 2 setvcp 10 100 && ddcutil -d 2 getvcp 10
VCP code 0x10 (Brightness ): current value = 100, max
value = 100
$ systemctl --user restart plasma-powerdevil.service
$ ddcutil -d 2 getvcp 10
VCP code 0x10 (Brightness ): current value = 30, max
value = 100
```
It turns back to 30%. I think this problem may caused by Powerdevil, by
according to #452492, this problem should already by solved in plasma 6.4.0?
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