Comment 0 for bug 1354313

This is a system installed with latest stable 12.04.5 image.

The Brightness key will invoke the osd-notify indicator but the display brightness won't change.

Verifying the value changing in backlight interface, system are using acpi_video0 instead:

Steps to monitor the backlight interfaces:

Press the brightness key until maxium indicator shows:

ubuntu@201210-11863:/sys/class/backlight$ cat intel_backlight/brightness ; cat acpi_video0/brightness
3407
99
ubuntu@201210-11863:/sys/class/backlight$

Press the brightness key until to minimum indicator shows:

ubuntu@201210-11863:/sys/class/backlight$ cat intel_backlight/brightness ; cat acpi_video0/brightness
3407
0

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: xorg 1:7.6+12ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-32.57~precise1-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
CompositorRunning: compiz
Date: Fri Aug 8 03:51:43 2014
DistUpgraded: Fresh install
DistroCodename: precise
DistroVariant: ubuntu
DkmsStatus: fwts-efi-runtime-dkms, 14.07.00, 3.13.0-32-generic, x86_64: installed
ExtraDebuggingInterest: Yes, even including gdb or git bisection work if needed
GraphicsCard:
 Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:05ba]
 Advanced Micro Devices, Inc. [AMD/ATI] Mars [Radeon HD 8730M] [1002:6601] (rev ff) (prog-if ff)
InstallationMedia: Ubuntu 12.04.5 LTS "Precise Pangolin" - Release amd64 (20140807.1)
MachineType: Dell Inc. Inspiron 5721
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-32-generic root=UUID=93a24f68-72a1-4335-938a-75f624f57e68 ro quiet splash initcall_debug vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/25/2013
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A12
dmi.board.name: 0KNF68
dmi.board.vendor: Dell Inc.
dmi.board.version: X01
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A12
dmi.modalias: dmi:bvnDellInc.:bvrA12:bd10/25/2013:svnDellInc.:pnInspiron5721:pvrA12:rvnDellInc.:rn0KNF68:rvrX01:cvnDellInc.:ct8:cvrA12:
dmi.product.name: Inspiron 5721
dmi.product.version: A12
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.7.12-0ubuntu4
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1~precise1
version.libgl1-mesa-dri: libgl1-mesa-dri N/A
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A