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[Bug 1486896] Re: On Lenovo Thinkpad Edge E330, the screen backlight flickers badly.


Mark, the next step is to fully reverse commit bisect from kernel 4.2 to
4.4-rc4 in order to identify the last bad commit, followed immediately
by the first good one. Once this commit has been identified, then it may
be reviewed as a candidate for backporting into your release. Could you
please do this following

Please note, finding adjacent kernel versions is not fully commit

Thank you for your understanding.

Helpful bug reporting tips:

** Tags removed: kernel-bug-fixed-upstream kernel-bug-fixed-upstream-4.4-rc4
** Tags added: kernel-fixed-upstream kernel-fixed-upstream-4.4-rc4

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

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

Status in linux package in Ubuntu:

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

  Steps were taken according to this:

  With acpi_backlight=vendor, the flicker stops, and the brightness control doesn't work.
      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
   /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
   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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