Powerdevil isn't enabling external monitor brightness controls in the Battery applet despite ddcutil being detected during compile time. ddcutil detects my external monitor and I can change its brightness values with ddcutil manually. PowerDevil service starts without issue, though there are these odd errors in journalctl: Feb 04 17:26:58 archlinux org_kde_powerdevil[483180]: org.kde.powerdevil: org.kde.powerdevil.backlighthelper.brightness failed Feb 04 17:26:58 archlinux org_kde_powerdevil[483180]: org.kde.powerdevil: The profile "AC" tried to activate "BrightnessControl" a non-existent action. This is usually due to an installation problem, a configuration problem, or because the action is not supported
Was testing Powerdevil again, and realized my previous comment's log output may not have been sufficient: Feb 10 19:04:08 archlinux systemd[2190]: Starting Powerdevil... Feb 10 19:04:08 archlinux libddcutil[31409]: Initializing. ddcutil version 1.3.0 Feb 10 19:04:08 archlinux libddcutil[31409]: Library initialization complete. Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Activating service name='org.kde.powerdevil.discretegpuhelper' requested by ':1.259' (uid=1000 pid=31409 comm="/run/media/valmar/DataSSD/KDE/usr-20230204-1700/li") (using servicehelper) Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Successfully activated service 'org.kde.powerdevil.discretegpuhelper' Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Activating service name='org.kde.powerdevil.chargethresholdhelper' requested by ':1.259' (uid=1000 pid=31409 comm="/run/media/valmar/DataSSD/KDE/usr-20230204-1700/li") (using servicehelp> Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Successfully activated service 'org.kde.powerdevil.chargethresholdhelper' Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Activating service name='org.kde.powerdevil.backlighthelper' requested by ':1.259' (uid=1000 pid=31409 comm="/run/media/valmar/DataSSD/KDE/usr-20230204-1700/li") (using servicehelper) Feb 10 19:04:08 archlinux backlighthelper[31441]: org.kde.powerdevil: no kernel backlight interface found Feb 10 19:04:08 archlinux dbus-daemon[708]: [system] Successfully activated service 'org.kde.powerdevil.backlighthelper' Feb 10 19:04:08 archlinux org_kde_powerdevil[31409]: org.kde.powerdevil: org.kde.powerdevil.chargethresholdhelper.getthreshold failed "Charge thresholds are not supported by the kernel for this hardware" Feb 10 19:04:08 archlinux org_kde_powerdevil[31409]: org.kde.powerdevil: org.kde.powerdevil.backlighthelper.brightness failed Feb 10 19:04:08 archlinux systemd[2190]: Started Powerdevil. Feb 10 19:04:08 archlinux org_kde_powerdevil[31409]: org.kde.powerdevil: The profile "AC" tried to activate "BrightnessControl" a non-existent action. This is usually due to an installation problem, a configuration problem, or because the> Feb 10 19:04:08 archlinux org_kde_powerdevil[31409]: org.kde.powerdevil: org.kde.powerdevil.chargethresholdhelper.getthreshold failed "Charge thresholds are not supported by the kernel for this hardware"
Based on these logs, no backlight interface was found which means that PowerDevil would use libddcutil displays. The fact that the "BrightnessControl" action is reported as non-existent probably means that no display was added to PowerDevil's list even after querying libddcutil. I don't know why your monitor would not show up in the list. Plasma 6.1 will have a lot of improvements on the libddcutil side, including better handling of display connect/disconnect events and more informative logs. But it's not out yet. Plasma 6.0 probably still behaves substantially the same as a year ago when this was reported. You could try getting more detailed PowerDevil logs by following the instructions in the new README: https://invent.kde.org/plasma/powerdevil/-/blob/master/README.md That could at least confirm that no displays were added to the list, but I can't guarantee that the logs will provide many further insights than that.
Is this bug still happening on Plasma 6.3.2 or later?
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