I have a ThinkPad X1 Yoga (2nd gen) and when running Ubuntu 17.04 I could change the brightness like this:
$ xrandr --output eDP-1 --brightness .7
Now, when I do that under 17.10 I get this:
warning: output eDP-1 not found; ignoring
xrandr: Need crtc to set gamma on.
When I hit brightness up and down buttons I see the numerical value in this file changing properly:
/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness
But xrandr reports a new label:
$ xrandr -q
Screen 0: minimum 320 x 200, current 2560 x 1440, maximum 8192 x 8192
XWAYLAND0 connected 2560x1440+0+0 (normal left inverted right x axis y axis) 310mm x 180mm
2560x1440 59.96*+
I've tried replacing eDP-1 with XWAYLAND0 but it returns 0 with no errors and nothing at all happens to the brightness.
$ xrandr --output XWAYLAND0 --brightness 0.5
$ echo $?
0
Would love some help on getting brightness settings working again. Right now it's stuck on full brightness all the time, which isn't great for the battery.