backlight control not working on VAIO CW2C5E

Binary package hint: gnome-power-manager

Ubuntu can't control backlight on my laptop. This happened also in 10.04 and 10.10 and I had to fix this using nvidia_bl driver (and it took quite a lot of time to set the correct parameters. Other function keys work properly.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: gnome-power-manager 2.32.0-2ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-6.34-generic 2.6.38-rc7
Uname: Linux 2.6.38-6-generic x86_64
NonfreeKernelModules: nvidia
Architecture: amd64
Date: Fri Mar 11 18:40:30 2011
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GnomeSessionSuspendInhibited: No
MachineType: Sony Corporation VPCCW2C5E
ProcEnviron:
 LANGUAGE=it_IT:en
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-6-generic root=UUID=a84ea41e-433f-4492-a8f1-0be8f25ac870 ro quiet splash vt.handoff=7
SourcePackage: gnome-power-manager
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/14/2010
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: R0170Y7
dmi.board.asset.tag: N/A
dmi.board.name: VAIO
dmi.board.vendor: Sony Corporation
dmi.board.version: N/A
dmi.chassis.asset.tag: N/A
dmi.chassis.type: 10
dmi.chassis.vendor: Sony Corporation
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrR0170Y7:bd05/14/2010:svnSonyCorporation:pnVPCCW2C5E:pvrC603N5FU:rvnSonyCorporation:rnVAIO:rvrN/A:cvnSonyCorporation:ct10:cvrN/A:
dmi.product.name: VPCCW2C5E
dmi.product.version: C603N5FU
dmi.sys.vendor: Sony Corporation