Public bug reported: On an Acer Aspire V5 with Intel Graphics, backlight control is not working. Both on Ubuntu GNOME 13.10 and 14.04 neither hotkeys or adjusting the applet slider has any effect. Note that the hotkeys Fn+Left and Fn+Right DO result in a moving slider indicator (this will change after testing with kernel parameters!) but no actual backlight change.
Following https://wiki.ubuntu.com/Kernel/Debugging/Backlight "Testing for a workaround" here are my findings. More debugging info will be attached later. TESTING FOR A WORK AROUND > Reboot with only the kernel parameter acpi_backlight=vendor : > Make a comment on if you can now alter the backlight with hotkeys or a > brightness applet. No / Yes * > sudo su > echo 8 > /sys/class/backlight/intel_backlight/brightness > Please comment on if the brightness changes. Yes > Reboot with just kernel parameter video.use_bios_initial_backlight=0 > and make a comment on if you can now alter the backlight with hotkeys or a > brightness applet. No / Yes * > If using a v3.13.x+ series kernel, reboot with just kernel parameter > video.use_native_backlight=1 > and make a comment on if you can now alter the backlight with hotkeys or a > brightness applet. No / Yes * > If your backlight hotkeys are Fn+Left and Fn+Right, add kernel parameter atkbd.softraw=0 to /boot/grub/menu.lst They are so I did (not /boot/grub/menu.lst but /etc/default/grub though...) and I rebooted even though it is not written I should... > Then, switch to any console, e.g. Ctrl+Alt+F1, login by root account and execute: showkey -s I did (after reboot mentioned above) and found that the hotkeys do not give any output at all anymore... Strange. So I reverted all changed above and rebooted with only "quiet splash" boot parameters but still the hotkeys remain dead. Not even the faux brightness slider change anymore. Very strange! * please note that there is no brightness applet in Ubuntu GNOME 14.04 but going to the Settings > Screen Brightness & Lock the brightness can now be controlled BASIC DEBUGGING INFORMATION (all files will be attached later) $ ls /sys/class/backlight intel_backlight Note that this used to list video0_backlight (as I remember it) too but after testing and reverting (!) that entry remains gone. Strange. $ dmesg | grep 'ACPI: Video' [ 2.969975] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) $ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) $ cat /proc/version Linux version 3.13.0-24-generic (buildd@panlong) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-24-generic 3.13.0-24.46 ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9 Uname: Linux 3.13.0-24-generic x86_64 ApportVersion: 2.14.1-0ubuntu3 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: ravanhagen 1918 F.... pulseaudio CurrentDesktop: GNOME Date: Fri Apr 18 12:03:12 2014 EcryptfsInUse: Yes InstallationDate: Installed on 2014-04-14 (3 days ago) InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Daily amd64 (20140406) MachineType: Acer Aspire V5-571P ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic.efi.signed root=UUID=631fc653-5697-44cb-b877-f6cae0fda9cf ro acpi_backlight=vendor quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-24-generic N/A linux-backports-modules-3.13.0-24-generic N/A linux-firmware 1.127 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/16/2012 dmi.bios.vendor: Phoenix Technologies Ltd. dmi.bios.version: V2.13 dmi.board.asset.tag: No Asset Tag dmi.board.name: Aspire V5-571P dmi.board.vendor: Acer dmi.board.version: V2.13 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: Acer dmi.chassis.version: V2.13 dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvrV2.13:bd11/16/2012:svnAcer:pnAspireV5-571P:pvrV2.13:rvnAcer:rnAspireV5-571P:rvrV2.13:cvnAcer:ct9:cvrV2.13: dmi.product.name: Aspire V5-571P dmi.product.version: V2.13 dmi.sys.vendor: Acer ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug trusty ** Attachment added: "grep -r . /proc/acpi > acpi" https://bugs.launchpad.net/bugs/1309462/+attachment/4087185/+files/acpi -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1309462 Title: Intel Ivybridge Mobile graphics backlight not adjustable To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1309462/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
