SUMMARY For as long as I can remember, the OSD popup that comes when I press a key to raise or lower laptop LCD screen backlight brightness has been wonky. For one, the brightness starts changing as soon as I press the key, but the OSD takes so long coming up that when it does, then it changes my brightness back to where it was before I started changing it and I have to do it all over again. Another very common occurrence is that the backlighthelper (/usr/lib/kauth/libexec/backlighthelper) process hangs, so the OSD does not go away and the program continues eating CPU. The only remedy I've found that often works to stop backlighthelper is to press another OSD-related key, such as turning the touchpad off and back on. It's so unusable that I've finally wised up and renamed backlighthelper so the system can't find it. No OSD now, but it's an improvement otherwise. Also, the lagginess of the program often interprets a single quick keystroke as if I had held the key down, so one quick press makes the screen go all the way bright or all the way dim. STEPS TO REPRODUCE 1. Press the <Monitor Brightness Down> or <Monitor Brightness Up> keys. OBSERVED RESULT Brightness changes immediately. Eventually OSD comes up and changes brightness back to where it was until I press the key again with the OSD on screen. Often, backlighthelper hangs and must be killed or interrupted by pressing another key that raises another OSD notification. A single quick press may result in the screen being completely dimmed or brightened instead of changing brightness by just one level. EXPECTED RESULT The program obviously isn't needed to change the brightness, so when it fights me by changing the brightness back, that's lemon juice in the paper cut. Why can't it just report the change I've already made, when it finally gets around to it, and then just get off the screen and let me work? It doesn't need to be actually changing ANYTHING, let alone misinterpreting my keyboard input or hanging indefinitely. SOFTWARE/OS VERSIONS Kubuntu 20.04 64-bit KDE Plasma Version: 5.18.8 KDE Frameworks Version: 5.68.0 Qt Version: 5.12.8 Powerdevil: 5.18.6 ADDITIONAL INFORMATION Available on request. If there's something I can run that will give you helpful info, let me know.
1. One issue per bug report please. 2. The version of Plasma you're using is old and no longer supported; can you upgrade to Kubuntu 22.04 (which has Plasma 5.24, the latest LTS version) and see if it's still happening there?
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I don't have time to reinstall at the moment. Tried Kubuntu 21.10 and 22.04 via live CD. Couldn't reproduce backlighthelper hanging with either. 21.10 was still slow and fought back. 22.04 was significantly more responsive. The issue of it going back a step or too may still exist, but it's much less of a problem due to the improved performance. Thanks.