Comment 91 for bug 1007765

On Sun, Jun 23, 2013 at 04:59:03AM -0000, Savio wrote:
> Thats help, but adding this line in /etc/rc.local before exit 0 statement making brigthness hotkey unusable.

This couldn't be caused by disabling nmi_watchdog; this is totally unrelated.

My guess is that you've booted the system with acpi_backlight=vendor which
disabled the ACPI backlight interface (/sys/class/backlight/acpi_video0), and
enabled the interface for the vendor backlight driver (e.g.,
/sys/class/backlight/dell_backlight) which won't be picked up by X, because
it's not hard-coded to use it. So, you ended up with no backlight interface for
X to use. That's why the hotkeys seem to be not working.

Try booting the kernel without acpi_backlight=vendor, while disabling
nmi_watchdog from /etc/rc.local as before, and let's see what would happen.

> will adding this

> Section "Device"
> Identifier "Intel Graphics"
> Driver "intel"
> Option "AccelMethod" "sna"
> Option "Backlight" "intel_backlight"
> Identifier "Card0"
> Driver "intel"
> BusID "PCI:0:2:0"
> EndSection

Yes, I think this would help, but I haven't tried it before.