I spoke a bit too soon it seems. It had been working fine. Just now I left my laptop for ~5 minutes (it was on, screen open, brightness on full when I left).
I came back and found the brightness stuck on minimum (and my session had timed out, prompting me for my password - presumably something that happened as part of the time out is what triggered this bug and thus the brightness to be stuck on minimum). Echoing 0 to /sys/class/backlight/intel_backlight/brightness did not fix it. Suspending and unsuspending the laptop did fix it - the brightness was back at full when I unsuspended, and I have control again. I seem to recall reading either further up on here or elsewhere that the root cause is/was a race condition. I know next to nothing about things at this level (my current expertise is in Android and at the SDK level) but what I saw just now seemed like it could be explained in terms of a race condition. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/954661 Title: backlight brightness not adjustable by default on Dell XPS 13 Status in Dell Sputnik: New Status in “linux” package in Ubuntu: Fix Released Status in “linux” source package in Precise: In Progress Status in “linux” source package in Quantal: In Progress Status in “linux” source package in Raring: Fix Released Bug description: The backlight brightness is not changeable by default on a Dell XPS 13 running Precise beta 1 (or later). If I run the following command as root, I can adjust the brightness: /bin/echo 0 > /sys/class/baclight/intel_backlight/brightness However, I must do this whenever I turn on the computer or resume it from suspend. ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: xserver-xorg-video-intel 2:2.17.0-1ubuntu4 ProcVersionSignature: Ubuntu 3.2.0-18.29-generic 3.2.9 Uname: Linux 3.2.0-18-generic x86_64 .tmp.unity.support.test.0: ApportVersion: 1.94.1-0ubuntu2 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: None Date: Tue Mar 13 20:56:36 2012 DistUpgraded: Fresh install DistroCodename: precise DistroVariant: ubuntu ExtraDebuggingInterest: Yes, whatever it takes to get this fixed in Ubuntu GraphicsCard: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller]) Subsystem: Dell Device [1028:052e] InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120301) MachineType: Dell Inc. Dell System XPS L321X ProcEnviron: TERM=xterm LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-18-generic root=UUID=6a0a6c9c-fb29-446a-8806-e431d38c95e8 ro quiet splash i915.i915_enable_fbc=1 i915.i915_enable_rc6=1 pcie_aspm=force vt.handoff=7 SourcePackage: xserver-xorg-video-intel UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 01/30/2012 dmi.bios.vendor: Dell Inc. dmi.bios.version: A02 dmi.board.name: 085X6F dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: 0.1 dmi.modalias: dmi:bvnDellInc.:bvrA02:bd01/30/2012:svnDellInc.:pnDellSystemXPSL321X:pvr:rvnDellInc.:rn085X6F:rvrA00:cvnDellInc.:ct8:cvr0.1: dmi.product.name: Dell System XPS L321X dmi.sys.vendor: Dell Inc. version.compiz: compiz 1:0.9.7.0+bzr3035-0ubuntu1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.30-1ubuntu1 version.libgl1-mesa-dri: libgl1-mesa-dri 8.0.1-0ubuntu2 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 8.0.1-0ubuntu2 version.xserver-xorg-core: xserver-xorg-core 2:1.11.4-0ubuntu6 version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:22.214.171.1241+git20120126-0ubuntu2 version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.99~git20111219.aacbd629-0ubuntu2 version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.17.0-1ubuntu4 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20111201+b5534a1-1build2 To manage notifications about this bug go to: https://bugs.launchpad.net/dell-sputnik/+bug/954661/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : firstname.lastname@example.org Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp