Comment 0 for bug 1403792

Without noticible cause the brightness of the screen of my laptop is no longer adjustable and stuck at the lowest level. Both the hotkey on my keyboard and the brightness submenu in the system settings no longer show any reaction to changes (i.e. key pressing and using the regulation bar in the menu).

The issue persists after rebooting which makes the main screen of my laptop unusable and it necessary to plug in an extra monitor!

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: unity 7.3.1+14.10.20141016-0ubuntu1
Uname: Linux 3.17.6-031706-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
CurrentDmesg: Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: Permission denied
Date: Thu Dec 18 10:06:33 2014
DistUpgraded: Fresh install
DistroCodename: utopic
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:3904]
MachineType: LENOVO 20221
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.17.6-031706-generic root=UUID=27047ee0-b60c-4dc6-8c14-f416b264f331 ro
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/12/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 71CN51WW(V1.21)
dmi.board.asset.tag: No Asset Tag
dmi.board.name: INVALID
dmi.board.vendor: LENOVO
dmi.board.version: 31900003WIN8 STD MLT
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo IdeaPad Z500 Touch
dmi.modalias: dmi:bvnLENOVO:bvr71CN51WW(V1.21):bd07/12/2013:svnLENOVO:pn20221:pvrLenovoIdeaPadZ500Touch:rvnLENOVO:rnINVALID:rvr31900003WIN8STDMLT:cvnLENOVO:ct10:cvrLenovoIdeaPadZ500Touch:
dmi.product.name: 20221
dmi.product.version: Lenovo IdeaPad Z500 Touch
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.58+git20141201.f99522e6-0ubuntu0ricotz
version.libgl1-mesa-dri: libgl1-mesa-dri 10.5.0~git20141210.47aaabda-0ubuntu0ricotz~utopic
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.5.0~git20141210.47aaabda-0ubuntu0ricotz~utopic
version.xserver-xorg-core: xserver-xorg-core 2:1.16.1.901-1ubuntu1~utopic1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.99+git20140806.fbf575cb-0ubuntu0sarvatt3
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.916+git20141215.99537089-0ubuntu0sarvatt~utopic
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11+git20141030.3fb97d78-0ubuntu0sarvatt
xserver.bootTime: Thu Dec 18 10:05:52 2014
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 5557
 vendor CMN
xserver.version: 2:1.16.1.901-1ubuntu1~utopic1