Comment 0 for bug 1389215

Brightness controls are not working in Unity / Xorg. When pressing the keys <fn><home> and <fn><end> on my Lenovo W510, I see the indicator on the screen showing the level of brightness changing, so key mapping is not the problem. However, the brightness is not changing.

On the kernel level, I have the single following device:

# cd /sys/class/backlight
# ls -l
total 0
lrwxrwxrwx 1 root root 0 Nov 3 17:16 acpi_video0 -> ../../devices/pci0000:00/0000:00:03.0/0000:01:00.0/backlight/acpi_video0

When playing with the <fn><home> and <fn><end>, the value of /sys/class/backlight/brightness changes accordingly. The screen brightness does not change.

Performing:

# echo 10 >brightness

...does not have any effect (regardless of the value provided, 10 being just an example).

WORKAROUND

There is an odd workaround. Simply go to the console using <CTRL><ALT><F1> and using the <fn><home> and <fn><end> keys, brightness then changes. Return to Unity / Xorg with <CTRL><ALT><F7> and the selected brightness persists.

NON WORKING WORKAROUND

On the web, I read that adding:

Option "RegistryDwords" "EnableBrightnessControl=1"'

in xorg.conf might fix the problem. I do not have an xorg and when I let the proprietary Nvidia driver generate one and add this option, X does not start anymore.

Ubuntu 14.04.1 LTS with latest updates as of this writing.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xorg 1:7.7+1ubuntu8
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 331.38 Wed Jan 8 19:32:30 PST 2014
 GCC version: gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
.tmp.unity.support.test.0:

ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,compiztoolbox,decor,place,put,snap,resize,move,regex,session,vpswitch,imgpng,gnomecompat,text,ring,grid,mousepoll,animation,unitymtgrabhandles,wall,expo,ezoom,workarounds,fade,scale,unityshell]
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Nov 4 07:38:59 2014
DistUpgraded: Fresh install
DistroCodename: trusty
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.7, 3.13.0-32-generic, x86_64: installed
 bbswitch, 0.7, 3.13.0-39-generic, x86_64: installed
 nvidia-331, 331.38, 3.13.0-32-generic, x86_64: installed
 nvidia-331, 331.38, 3.13.0-39-generic, x86_64: installed
 tp-smapi, 0.41, 3.13.0-32-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GraphicsCard:
 NVIDIA Corporation GT216GLM [Quadro FX 880M] [10de:0a3c] (rev a2) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:2145]
InstallationDate: Installed on 2014-11-01 (3 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: LENOVO 4318CTO
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-39-generic root=UUID=994f9c2c-f967-472e-ace3-23cd620ec702 ro quiet splash
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/03/2012
dmi.bios.vendor: LENOVO
dmi.bios.version: 6NET84WW (1.45 )
dmi.board.name: 4318CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6NET84WW(1.45):bd10/03/2012:svnLENOVO:pn4318CTO:pvrThinkPadW510:rvnLENOVO:rn4318CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 4318CTO
dmi.product.version: ThinkPad W510
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.11.2+14.04.20140714-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.3-0ubuntu0.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.3-0ubuntu0.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.15.1-0ubuntu2.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Tue Nov 4 01:40:35 2014
xserver.configfile: default
xserver.errors: open /dev/fb0: No such file or directory
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.15.1-0ubuntu2.1