Cannot adjust brightness via keyboard after suspending without a display manager
Decided to uninstall my display manager and use startx instead. But now when I resume from suspend, the brightness keys cease to work until I log out and back in. Backlight does still respond when echoing into /sys/class/backlight/intel_backlight/brightness. But what kind of magic does a display manager do to keep brightness controls working after suspend and resume?
My 2012 MacBook Pro has exactly the opposite behaviour on a clean install across multiple distros. The brightness keys do nothing until after a suspend, then work fine until the next reboot. Never found a fix.