Also, if the "Enable Switchable Graphics" option in BIOS is set to true, the brightness control would work. This option will make two more backlight interface available. ubuntu@201305-13527:~$ ls /sys/class/backlight/ acpi_video0 acpi_video1 intel_backlight
-- 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/1411514 Title: [Dell Precision M4800] Brightness can't be controlled on 14.04.1 Status in HWE Next Project: New Status in linux package in Ubuntu: Confirmed Bug description: CID: 201305-13527 Dell Precision M4800 The screen brightness The brightness control does not work at all on 14.04.1 Steps: 1. Install 14.04.1 + update 2. Test the brightness control with hotkeys 3. Test the brightness control by using the "Brightness and Lock" applet. Expected results: * Brightness control should work in step 2 and 3 Actual result: * Brightness level would change with the hotkey, but the backlight level won't, nothing happened when you scroll the scrollbar in the "Brightness and Lock" applet. Debugging information: ubuntu@201305-13527:~$ sudo showkey -s kb mode was ?UNKNOWN? [ if you are trying this under X, it might not work since the X server is also reading /dev/console ] press any key (program terminates 10s after last keypress)... 0x9c 0xe0 0x54 0xe0 0xd4 0xe0 0x4c 0xe0 0xcc 0x1d ^Ccaught signal 2, cleaning up... ubuntu@201305-13527:~$ ubuntu@201305-13527:~$ sudo showkey -k kb mode was ?UNKNOWN? [ if you are trying this under X, it might not work since the X server is also reading /dev/console ] press any key (program terminates 10s after last keypress)... keycode 28 release keycode 225 press keycode 225 release keycode 224 press keycode 224 release keycode 29 press ^Ccaught signal 2, cleaning up... ubuntu@201305-13527:~$ ubuntu@201305-13527:~$ ls /sys/class/backlight/ acpi_video0 ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-44-generic 3.13.0-44.73 ProcVersionSignature: Ubuntu 3.13.0-44.73-generic 3.13.11-ckt12 Uname: Linux 3.13.0-44-generic x86_64 ApportVersion: 2.14.1-0ubuntu3.6 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: ubuntu 1635 F.... pulseaudio ubuntu 2242 F.... pulseaudio /dev/snd/controlC0: ubuntu 1635 F.... pulseaudio ubuntu 2242 F.... pulseaudio CRDA: country TW: (2402 - 2472 @ 40), (3, 27) (5270 - 5330 @ 40), (3, 17), DFS (5735 - 5815 @ 40), (3, 30) CurrentDesktop: Unity Date: Fri Jan 16 00:56:25 2015 HibernationDevice: RESUME=UUID=4e3c0183-4d3f-495e-8d6a-57e2b23e6412 InstallationDate: Installed on 2015-01-16 (0 days ago) InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417) MachineType: Dell Inc. Precision M4800 ProcFB: 0 nouveaufb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-44-generic root=UUID=3edd6366-27b1-41af-88d4-ac1abe216d8f ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-44-generic N/A linux-backports-modules-3.13.0-44-generic N/A linux-firmware 1.127.11 RfKill: 0: phy0: Wireless LAN Soft blocked: no Hard blocked: no SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/03/2014 dmi.bios.vendor: Dell Inc. dmi.bios.version: A11 dmi.board.name: 0FVDR2 dmi.board.vendor: Dell Inc. dmi.board.version: X02 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA11:bd12/03/2014:svnDellInc.:pnPrecisionM4800:pvr01:rvnDellInc.:rn0FVDR2:rvrX02:cvnDellInc.:ct9:cvr: dmi.product.name: Precision M4800 dmi.product.version: 01 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1411514/+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
