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[Jingguo Yao <1320659@xxxxxxxxxxxxxxxxxx>]

I also have this problem. I am using Ubuntu 14.04 64 bit with a Thinkpad
T440S.

At the beginning, I have the following four problems:

1. After every boot, the brightness is set to maximum.
2. The brightness can't be adjusted smoothly. Only 4 brightnesses can be achieved with Fn keys.
3. After recovering from dimming, the brightness is set to maximum.
4. The following error message is printed during the boot:
[   12.843633] thinkpad_acpi: Unsupported brightness interface, please contact ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx

The following workaround fixes 1 for me.
http://askubuntu.com/questions/151651/brightness-is-reset-to-maximum-on-every-restart

I add "acpi_backlight=vendor" kernel parameter according to
https://wiki.ubuntu.com/Kernel/Debugging/Backlight. This fixes 2 and 3
for me.

But 4 still exists.

-- 
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/1320659

Title:
  [Lenovo ThinkPad Edge E430] "thinkpad unsupported brightness
  interface" message is showing while booting up

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  While I have no actual problem with adjusting the brightness, I've noticed a message that displays while booting up:
  "thinkpad unsupported brightness interface" 

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: linux-image-3.13.0-24-generic 3.13.0-24.47
  ProcVersionSignature: Ubuntu 3.13.0-24.47-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:  tarunp     2026 F.... pulseaudio
  CurrentDesktop: Unity
  Date: Sun May 18 21:18:35 2014
  HibernationDevice: RESUME=UUID=7769c1de-f761-42a1-841a-41dd723f7046
  InstallationDate: Installed on 2014-04-21 (26 days ago)
  InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
  MachineType: LENOVO 3254T1Q
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic root=UUID=5d9a6cf6-1023-43f0-82b8-7df33d90132e ro acpi_osi=Linux quiet splash acpi_backlight=vendor 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: 10/22/2012
  dmi.bios.vendor: LENOVO
  dmi.bios.version: H0ET72WW (2.06 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 3254T1Q
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Available
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvrH0ET72WW(2.06):bd10/22/2012:svnLENOVO:pn3254T1Q:pvrThinkPadEdgeE430:rvnLENOVO:rn3254T1Q:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 3254T1Q
  dmi.product.version: ThinkPad Edge E430
  dmi.sys.vendor: LENOVO

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