Comment 0 for bug 875893

Backlight hotkeys are registered and OSD shows backlight level going up and down but there is no effect on actual backlight level.

Following the debugging instructions here: <https://wiki.ubuntu.com/Kernel/Debugging/Backlight>, I have added the kernel boot parameter "acpi_backlight=vendor" and this makes the backlight work as expected.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-3.0.0-12-generic 3.0.0-12.20
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC269 Analog [ALC269 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC269 Analog [ALC269 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: andrzej 1460 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xf0400000 irq 47'
   Mixer name : 'Realtek ALC269'
   Components : 'HDA:10ec0269,144dc072,00100004'
   Controls : 14
   Simple ctrls : 9
Date: Sun Oct 16 19:15:03 2011
HibernationDevice: RESUME=UUID=86d5ebb5-f2d7-4c81-89f6-11aad8001fd9
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MachineType: SAMSUNG ELECTRONICS CO., LTD. N150P
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-12-generic root=UUID=828f538c-35f0-4bfb-b594-4d72b443e430 ro quiet splash vt.handoff=7 acpi_backlight=vendor
RelatedPackageVersions:
 linux-restricted-modules-3.0.0-12-generic N/A
 linux-backports-modules-3.0.0-12-generic N/A
 linux-firmware 1.60
SourcePackage: linux
StagingDrivers: brcmsmac brcmutil
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/20/2010
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: 01GT.M026.20101220.RHU
dmi.board.asset.tag: SAMSUNG
dmi.board.name: N150P
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr01GT.M026.20101220.RHU:bd12/20/2010:svnSAMSUNGELECTRONICSCO.,LTD.:pnN150P:pvrNotApplicable:rvnSAMSUNGELECTRONICSCO.,LTD.:rnN150P:rvrNotApplicable:cvnSAMSUNGELECTRONICSCO.,LTD.:ct10:cvrN/A:
dmi.product.name: N150P
dmi.product.version: Not Applicable
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.