The biggest issue is I have to previously "rmmod sony-laptop" on my Vaio VPCCW1, for nvidiabl to work.
Seems like there is a sort of priority in how udev/upower see backlight devices, and they always use /sys/class/backlight/sony when it's present, instead of /sys/class/backlight/nvidia_backlight
Unfortunately sony-laptop does other things besides (trying to) handle backlight on a Sony, and keeping it blacklisted is a bad option. I haven't found any option to disable its backlight handling functions either
Is there any way to have both modules loaded at same time and KDE4 pick the correct backlight interface?
I had found a solution with hal by means of a configuration in /etc/hal/fdi/policy, but this is no longer possible with udev/upower.