Comment 11 for bug 847001

Interesting find!

FWIW, on my system, intel_backlight/brightness is fixed at 4319, but acpi_video0/brightness is also fixed at 14. I could change the value of acpi_video1/brightness from 0 to 15 by altering the brightness either with the keys on my USB keyboard, or by using "$ xbacklight -set n", where n is a number (0 to 100).

For some reason the internal keyboard's brightness buttons are not working at the moment, but I've been having 3 different kinds of Unity crashes almost every day, so there's no certainty that my system is currently 100% functional!