SUMMARY When using the keyboard backlight brightness slider in the kcm or the tray menu, only one arbitrary selected /sys/class/leds/*kbd_backlight* entry is controlled. Propably not the intended one when there are multiples. STEPS TO REPRODUCE 1. have more then one /sys/class/leds/*kbd_backlight* entry (e.g. a keyboard with a left, center, and right control zone) 2. slide the settings slider OBSERVED RESULT only one of the kbd_backlight is altered EXPECTED RESULT all kbd_backlight are adjustet or there is a way to select which oen should be adjusted SOFTWARE/OS VERSIONS Linux/KDE Plasma: Kernel 5.15, Plasma 5.26.5 ADDITIONAL INFORMATION I'm currently implementing a /sys/class/leds driver for a per key rgb and a 3 zone rgb keyboard On the 3 zone keyboard, druing boot the kbd_backlight device is set to 50%, but the slider in the tray controls kbd_backlight_2 after boot (the driver resisters kbd_backlight, kbd_backlight_1, kbd_backlight_2) On the per key keyboard there is kbd_backlight - kbd_backlight_125 (some are not connected to physical leds and are just reserved in the rgb controller, however i resiter them anyway for future proofing) Here the slider controlls kbd_backlight_59 (did not pay attention if any kbd_backlight is set to 50% after boot, but can look that up if relevant)
heh, not only keyboard backlights. It can't handle multiple screen with backlights either! I know that because I had to rewrite DDCUtils app to control my external monitor's brightness through app, and not via a DDC driver built into powerdevil/Plasma — otherwise I'd lose GUI access to control laptop's built-in screen brightness. (but this is a topic for a separate bug report)
Plasma doesn't control the keyboard backlight via sysfs directly, we go through the UPower DBus interface: https://upower.freedesktop.org/docs/KbdBacklight.html That has no notion of different devices afaik. I'd say the proper first thing to do would be to fix upower to apply the changes it gets from the DBus interface to all relevant devices. If we have a good story for actually exposing multiple controls in the UI we then can think about how to achieve that, either by fixing the UPower interface to support multiple devices or bypassing that entirely
opened a bug over at the upower bugtracker: https://gitlab.freedesktop.org/upower/upower/-/issues/237
I submitted a merge request to upower: https://gitlab.freedesktop.org/upower/upower/-/merge_requests/203
Nice!
Nice! From me too ^^