Comment 47 for bug 1229591

I installed today kernel 3.14.1. The problem is still present.

I have not tried yet kernel 3.15 as it is in a very early (RC2) stage yet.

I have also tried hundreds of grub parameters and conf files inside X11 (following the ARCH wiki here: https://wiki.archlinux.org/index.php/backlight) but still I could not make the brightness keys work.

My opinion is that this is clearly a kernel problem. Something that will not be fixed by just adding parameters in grub etc.
The buttons do not produce any kind of result in acpi_listen.

Since this function was working just fine in earlier kernels, it must mean that there is a change or breakage as regards this aspect in the newer kernels.