kernel-packages team mailing list archive

[Miles Lane <miles.lane@xxxxxxxxx>]

I am testing the Linus GIT development kernel.  Currently, my kernel build is 3.18.0-rc5+.
With this kernel, I get the following:

root@Wobbly:~# echo 938 > /sys/class/backlight/intel_backlight/brightness
bash: echo: write error: Invalid argument

root@Wobbly:~# echo 937 >
/sys/class/backlight/intel_backlight/brightness

As you can see, 937 is the highest value that does not give an error.

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https://bugs.launchpad.net/bugs/1392101

Title:
  Brightness controls not working on intel igfx

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  Brightness controls not working for me in Vivid Vervet as of 1-2 weeks ago.
  Was confirmed working on Utopic Unicorn.

  Hotkeys for brightness up & down non-functioning,
  Hotkey for display on/off still works.

  Gnome control center (brightness & lock) does not show brightness
  slider.

  What does work is
  "echo $value > /sys/class/backlight/intel_backlight/brightness"
  as root for any $value of 0 - 2047

  Running on an Asus S400C Laptop.

  kernel: 
  x86_64 3.16.0-24-generic

  lspci:
  00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)

  lsb_release:
  Description:	Ubuntu Vivid Vervet (development branch)
  Release:	15.04

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.16.0-24-generic 3.16.0-24.32
  ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
  Uname: Linux 3.16.0-24-generic x86_64
  ApportVersion: 2.14.7-0ubuntu10
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  martin     1970 F.... pulseaudio
  CurrentDesktop: Unity
  Date: Wed Nov 12 16:06:27 2014
  HibernationDevice: RESUME=UUID=a7b59988-1d75-4f19-8fd8-3c9a08c38e8d
  InstallationDate: Installed on 2014-08-21 (83 days ago)
  InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Alpha amd64 (20140820)
  MachineType: ASUSTeK COMPUTER INC. S400CA
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-24-generic.efi.signed root=UUID=e2aa386f-a710-4fb4-ba6e-5d233c6b7b25 ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.16.0-24-generic N/A
   linux-backports-modules-3.16.0-24-generic  N/A
   linux-firmware                             1.138
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 01/27/2014
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: S400CA.210
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: S400CA
  dmi.board.vendor: ASUSTeK COMPUTER INC.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK COMPUTER INC.
  dmi.chassis.version: 1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrS400CA.210:bd01/27/2014:svnASUSTeKCOMPUTERINC.:pnS400CA:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnS400CA:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
  dmi.product.name: S400CA
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK COMPUTER INC.

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