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[Asif Youssuff <yoasif@xxxxxxxxx>]

** Attachment added: "cat /proc/version > version"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388636/+attachment/4251602/+files/version

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https://bugs.launchpad.net/bugs/1388636

Title:
  Lenovo v570: Brightness not changing via UI widget in GNOME shell or
  hotkeys

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  Fresh install of a Vivid Vervet Ubuntu GNOME daily iso.

  Adding debugging information from
  https://wiki.ubuntu.com/Kernel/Debugging/Backlight

  I found that

  echo 8 > /sys/class/backlight/intel_backlight/brightness

  worked to lower my screen brightness, without playing with kernel
  parameters.

  Booting with the kernel parameter: acpi_backlight=vendor did not
  enable the UI widget or hotkeys, although echo 8 >
  /sys/class/backlight/intel_backlight/brightness continued to work.

  Booting with the kernel parameter: video.use_bios_initial_backlight=0
  did not allow for hotkey or widget changes of brightness.

  Booting with the kernel parameter: video.use_native_backlight=1

  Creating /usr/share/X11/xorg.conf.d/80-backlight.conf

  with the contents:

  Section "Device"
      Identifier  "Intel Graphics"
      Driver      "intel"
      Option      "AccelMethod"     "sna"
      Option      "Backlight"       "intel_backlight" # use your backlight that works here
      BusID       "PCI:0:2:0"
  EndSection

  and rebooting does resolve the issue.

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.16.0-24-generic 3.16.0-24.32 [modified: boot/vmlinuz-3.16.0-24-generic]
  ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
  Uname: Linux 3.16.0-24-generic x86_64
  ApportVersion: 2.14.7-0ubuntu9
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  asif       2318 F.... pulseaudio
  CurrentDesktop: GNOME
  Date: Sun Nov  2 15:48:05 2014
  HibernationDevice: RESUME=UUID=53025272-1910-418a-9f4a-b6ac00a768f1
  InstallationDate: Installed on 2014-11-01 (1 days ago)
  InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Alpha amd64 (20141031)
  MachineType: LENOVO 1066A9U
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.16.0-24-generic root=/dev/mapper/ubuntu--gnome--vg-root 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: 07/11/2011
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 44CN36WW
  dmi.board.asset.tag: Base Board Asset Tag
  dmi.board.name: Emerald Lake
  dmi.board.vendor: LENOVO
  dmi.board.version: FAB1
  dmi.chassis.asset.tag: Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: 0.1
  dmi.modalias: dmi:bvnLENOVO:bvr44CN36WW:bd07/11/2011:svnLENOVO:pn1066A9U:pvrLenovoV570:rvnLENOVO:rnEmeraldLake:rvrFAB1:cvnLENOVO:ct10:cvr0.1:
  dmi.product.name: 1066A9U
  dmi.product.version: Lenovo V570
  dmi.sys.vendor: LENOVO

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