Description of problem:
Can't control LCD backlight using laptop brightness keys in cinnamon

Version-Release number of selected component (if applicable):
2.6.3-4.fc22.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Press laptop keys to increase/decrease LCD backlight
2. OSD appears, confirming key press


Actual results:
Backlight does not change

Expected results:
Backlight should increase or decrease, according to the key pressed


Additional info:
Cinnamon settings daemon backlight helper (/usr/libexec/csd-backlight-helper) always crashes (segmentation fault), regardless of the parameters passed (--set-brightness XX, --get-brightness, --get-max-brightness).

Gnome settings daemon backlight helper (/usr/libexec/gsd-backlight-helper) works fine.