https://bugs.kde.org/show_bug.cgi?id=506946
Bug ID: 506946
Summary: KDE backlight on laptop screen gets max brightness
wrong
Classification: I don't know
Product: kde
Version First unspecified
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: unassigned-b...@kde.org
Reporter: kdeb...@vorpal.se
Target Milestone: ---
SUMMARY
I often use my laptop with external monitors. Recently screen backlight has
started to work for external monitors too. However, after a while (days) the
max brightness on the laptop monitor keeps going down. That is 100% according
to KDE is not 100%. The external monitors are unaffected. This keeps slowly
degrading over time, over many suspend/resume cycles.
root /sys/class/backlight/intel_backlight ❯ cat
/sys/class/backlight/intel_backlight/brightness
455
root /sys/class/backlight/intel_backlight ❯ cat
/sys/class/backlight/intel_backlight/max_brightness
1515
Yet Plasma claims this is 100%. If I manually write a higher value it works,
until I try to change it with plasma again, after which it keeps being broken.
For now I would be happy with a workaround where I disable KDE handling
backlight at all, if that is possible.
STEPS TO REPRODUCE
1. I have no idea. My best guess is: Use the computer over several days to
weeks, connecting and disconnecting external displays, putting the laptop in
suspend and resuming it.
2. Watch it degrade.
OBSERVED RESULT
Max brightness keeps going down
EXPECTED RESULT
100% brightness should keep being 100% brightness.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 6.4.2
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
* Kernel Version: 6.15.3-zen1-1-zen (64-bit)
* Graphics Platform: Wayland
* Processors: Intel® Core™ i7-8550U CPU @ 1.80GHz (4 cores, 8 threads)
* Memory: 32 GiB of RAM (31.0 GiB usable)
* Graphics Processor: Intel® UHD Graphics 620
ADDITIONAL INFORMATION
Lenovo Thinkpad T480
External monitors using Display Port with USB C adapter and HDMI (one of each).
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