[kde] [Bug 506946] New: KDE backlight on laptop screen gets max brightness wrong

[Vorpal]

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-bugs at kde.org
          Reporter: kdebugs at 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).

-- 
You are receiving this mail because:
You are the assignee for the bug.