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[Launchpad Bug Tracker <1486896@xxxxxxxxxxxxxxxxxx>]

[Expired for linux (Ubuntu) because there has been no activity for 60
days.]

** Changed in: linux (Ubuntu)
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1486896

Title:
  On Lenovo Thinkpad Edge E330, the screen backlight flickers badly.

Status in linux package in Ubuntu:
  Expired

Bug description:
  Behavior is the same on Ubuntu 14.04 -- 15.04.

  Steps were taken according to this:
  https://wiki.ubuntu.com/Kernel/Debugging/Backlight

  With acpi_backlight=vendor, the flicker stops, and the brightness control doesn't work.
  However,
      echo 8 > /sys/class/backlight/intel_backlight/brightness
  dims the screen.

  thinkpad-acpi.brightness_enable = 1 does nothing.

  Old workaround: If no changes are made to boot options, and
      echo 4437 > /sys/class/backlight/intel_backlight/brightness
  is done, the flicker stops and the GUI control / acpi_video0 works, but causes flicker again.

  Workaround 2: Kernel parameters: "thinkpad-acpi.brightness_enable=0
  acpi_backlight=vendor" fully fix the bug behavior and retain the
  brightness control.

  Issue: the intel_backlight device should be used, the workaround above
  disables the other devices, leaving only one, thus no conflicts occur.

  
  Attaching the necessary files.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.19.0-26-generic 3.19.0-26.28
  ProcVersionSignature: Ubuntu 3.19.0-26.28-generic 3.19.8-ckt4
  Uname: Linux 3.19.0-26-generic x86_64
  ApportVersion: 2.17.2-0ubuntu1.3
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  mark       1391 F.... pulseaudio
  CurrentDesktop: Unity
  Date: Thu Aug 20 11:21:39 2015
  HibernationDevice: RESUME=UUID=7a9e1f17-c57b-4e6f-bb0c-0b090b5d1405
  InstallationDate: Installed on 2014-08-22 (363 days ago)
  InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
  MachineType: LENOVO 3354DGG
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-26-generic root=UUID=b566feb2-5a5c-4573-8782-b78d130dbc45 ro quiet splash acpi_backlight=vendor vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.19.0-26-generic N/A
   linux-backports-modules-3.19.0-26-generic  N/A
   linux-firmware                             1.143.3
  SourcePackage: linux
  UpgradeStatus: Upgraded to vivid on 2015-08-20 (0 days ago)
  dmi.bios.date: 02/25/2013
  dmi.bios.vendor: LENOVO
  dmi.bios.version: H3ET72WW(1.09)
  dmi.board.asset.tag: Not Available
  dmi.board.name: 3354DGG
  dmi.board.vendor: LENOVO
  dmi.board.version: 0B98409 Std
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvrH3ET72WW(1.09):bd02/25/2013:svnLENOVO:pn3354DGG:pvrThinkPadEdgeE330:rvnLENOVO:rn3354DGG:rvr0B98409Std:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 3354DGG
  dmi.product.version: ThinkPad Edge E330
  dmi.sys.vendor: LENOVO

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