There's one ACPI related bug on 3.8 kernel, bug 1249978 According to Keng-Yu, this bug is related to brightness control through ACPI
-- 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/1250764 Title: [Dell Latitude E6440] Unable to adjust brightness on Precise Status in “linux” package in Ubuntu: Confirmed Bug description: CID: 201306-13688 Dell Latitude E6440 Backlight control does not work on Precise (3.2.0-56): 1. Hotkey event was not detected. 2. No scroll bar in brightness applet. 3. No entries in /sys/class/backlight. Steps: 1. Install 12.04.1 + update 2. Try to adjust the brightness by hotkeys 3. Try to adjust the brightness by the brightness applet Expected result: Brightness could be adjusted. Actual result: Hotkeys are not responding, no scroll bar in brightness applet. Debugging information: $ ls /sys/class/backlight > backlight (Nothing) $ dmesg | grep 'ACPI: Video' (Nothing) $ cat /proc/version Linux version 3.2.0-56-generic (buildd@roseapple) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #86-Ubuntu SMP Wed Oct 23 09:20:45 UTC 2013 Boot with "acpi_backlight=vendor" kernel parameter The hotkey could change the indicator level, and the scroll bar would appear in brightness applet. However, the brightness still cannot be altered. $ ls /sys/class/backlight/ dell_backlight Boot with "video.use_bios_initial_backlight=0" kernel parameter It behaves like without adding any other parameter. ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: linux-image-3.2.0-56-generic 3.2.0-56.86 ProcVersionSignature: Ubuntu 3.2.0-56.86-generic 3.2.51 Uname: Linux 3.2.0-56-generic x86_64 AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24. AplayDevices: **** List of PLAYBACK Hardware Devices **** card 1: PCH [HDA Intel PCH], device 0: ALC292 Analog [ALC292 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 ApportVersion: 2.0.1-0ubuntu17.6 Architecture: amd64 ArecordDevices: **** List of CAPTURE Hardware Devices **** card 1: PCH [HDA Intel PCH], device 0: ALC292 Analog [ALC292 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: ubuntu 1566 F.... pulseaudio Card0.Amixer.info: Card hw:0 'Intel'/'HDA Intel at 0xf7d34000 irq 43' Mixer name : 'Generic 0000 ID 0' Components : 'HDA:00000000,80860101,00100000' Controls : 0 Simple ctrls : 0 Card0.Amixer.values: Card1.Amixer.info: Card hw:1 'PCH'/'HDA Intel PCH at 0xf7d30000 irq 43' Mixer name : 'Realtek ALC292' Components : 'HDA:10ec0292,102805bd,00100001' Controls : 19 Simple ctrls : 10 Date: Wed Nov 13 03:16:25 2013 HibernationDevice: RESUME=UUID=aeb30de4-c85d-4d93-874d-8f06ce1303b2 InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1) MachineType: Dell Inc. Latitude E6440 MarkForUpload: True ProcEnviron: TERM=xterm PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 VESA VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-56-generic root=UUID=3cde48ea-3225-4afa-b02b-584a672a94e4 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.2.0-56-generic N/A linux-backports-modules-3.2.0-56-generic N/A linux-firmware 1.79.7 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 07/03/2013 dmi.bios.vendor: Dell Inc. dmi.bios.version: X23 dmi.board.name: 02P3T1 dmi.board.vendor: Dell Inc. dmi.board.version: X03 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrX23:bd07/03/2013:svnDellInc.:pnLatitudeE6440:pvr01:rvnDellInc.:rn02P3T1:rvrX03:cvnDellInc.:ct9:cvr: dmi.product.name: Latitude E6440 dmi.product.version: 01 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1250764/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
