Discovered another behaviour. If you play with the brightness controls under Xorg, nothing changes. However, suspend the computer and resume it, and the brightness will be setup to the last setup you left when playing with the brightness controls. Thus, the value in the kernel persists.
You can also test this with the CLI: # cd /sys/class/backlight/acpi_video0 # echo 10 >brightness # Nothing happens # cat actual_brightness 10 # echo 5 >brightness # Nothing happens # cat actual_brightness 5 <suspend computer> <resume computer> Now the brightness level is set to 5 and the screen finds itself at that level. In the backend, the controls are changing the brightness levels, it is just that during an Xorg Session with NVIDIA proprietary drivers, the screen's real brightness is not updated. As if the hardware signal to the screen is never sent, except when in the console or upon resume. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1389215 Title: Brightness controls are not working in Unity / Xorg because of Nvidia proprietary driver. Status in NVIDIA Drivers Ubuntu: New Status in “xorg” package in Ubuntu: New Bug description: 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 To manage notifications about this bug go to: https://bugs.launchpad.net/nvidia-drivers-ubuntu/+bug/1389215/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp