Turn backlight helper into a D-Bus system service
Submitted by Jan Alexander Steffens
Created attachment 315983 dbus backlight helper
The attached patch turns the backlight helper into a D-Bus system service. As a result, the brightness slider in GNOME Shell seems to be a lot less "laggy" (it occasionally seemed to have quite a lot of delay while dragging), and the journal isn't getting spammed with pkexec and PAM messages.
There's still lots of room for improvement - the GSD-side code creates a new GDBusProxy for every change of brightness, while the helper-side code only checks for the best device at startup and doesn't track the device's brightness for changes.
Maybe a proper backlight control service should be part of a lower component like systemd, instead? The latter already has a helper that provides brightness persistence across reboots.
Patch 315983, "dbus backlight helper":