Comment 15 for bug 921321

Rik

Can you please indicate what exactly do you mean with

"Brightness control does not work with this option for me."

Does it work before suspending the system?

Can you please attach your dmesg log, as it is the one relevant in this case (whereas xf86-video-nouveau, mesa and libdrm are not)

Auke, Rik

AFAIK brightness/backlight is(can be) controlled via
1. ACPI
2. platform specific - (asus-laptop, samsung-laptop, thinkpad ...)
3. the gpu/card itself

On various system different ones work correctly

By default nouveau does not register it's device if an ACPI one exists
Note that the blob has similar behaviour but they have an option to override it.

If you suspect that the ACPI backlight control is buggy you can disable it by appending "acpi_backlight=vendor" to your kernel command line

This will fall back to either 2. or 3. - dmesg will tell you which one

Feel free to give it a try

Cheers
Emil