asus-wmi for Asus G73SW

By default the brightness values are set to 10 (max_brightness) but changing any of them does not do anything (display stays at maximum brightness level).

Do you have an idea what could be missing?

I used acpi_backlight=vendor and /sys/class/backlight/asus-nb-wmi shows up as expected.

Also the kernel code that sets the brightness value in the asus-nb-wmi driver works (no error is returned, also the changed values show up in sysfs).
It just does not seem to get applied.

I found out that if after I switch to the console (alt+F1) changing the brightness in sysfs suddenly does have an effect.

Since I use the proprietary nvidia driver (for full OpenGL 3D support) I suspect that it has something to do with it.
I tried the Kubuntu Live installer CD which uses nouveau and changing the brightness works for Xorg there, too (even using the generic acpi_backlight code and the brightness value in acpi_video1).

I guess the Nvidia driver or something related to it is doing something nasty here which keeps the brightness from being applied. Switching back to Xorg from the console resets the value to 10 (I added some debug output to update_bl_status) so that's not a workaround unfortunately.

Since I have no idea what actual piece of hardware controls the backlight I wonder if it is part of the NVidia hardware and as soon as the nvidia driver takes over it will no longer accept updates from the BIOS?