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[Bug 1255014] Re: [Lenovo V480] Unable to control the brightness from Max - Min


** Tags added: latest-bios-1.16

** Package changed: linux-lts-raring (Ubuntu) => linux-lts-trusty

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  [Lenovo V480] Unable to control the brightness from Max - Min

Status in linux-lts-trusty package in Ubuntu:

Bug description:
  CID: 201204-10924 Lenovo V480

  With the Brightness applet, the brightness level on this system cannot be adjusted from Max (let's say, level 11) to Min (level 1).
  The brightness level will goes down and up, which behaves like 11-10-9-8-7-6-5-4-3-4-5

  1. Install 12.04.3 + update (3.8.0-33), boot to desktop
  2. Adjust the screen brightness by the Brightness and Lock applet, clicking the leftmost part of the scroll bar to change the brightness stepwise
  3. Click and drag the slider to adjust the brightness

  Expected result:
  - Brightness could be adjusted smoothly.

  Actual result:
  1. Brightness cannot go down to the lowest level, it behaves like 11-10-9-8-7-6-5-4-3-4-5
  2. When you drag and move the slider, the backlight will flash between Max and the indicated level.

  Debugging information:
  $ ls /sys/class/backlight
  acpi_video0@  intel_backlight@

  $ dmesg | grep 'ACPI: Video'
  [    7.104361] ACPI: Video Device [PEGP] (multi-head: no  rom: yes  post: no)
  [    7.107524] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post: no)

  $ cat /proc/version
  Linux version 3.8.0-33-generic (buildd@toyol) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #48~precise1-Ubuntu SMP Thu Oct 24 16:28:06 UTC 2013

  Note: the hotkey is probably affected by bug 1248442, but it will
  cause the same result when it's working.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: linux-image-3.8.0-33-generic 3.8.0-33.48~precise1
  ProcVersionSignature: Ubuntu 3.8.0-33.48~precise1-generic
  Uname: Linux 3.8.0-33-generic x86_64
  AlsaVersion: Advanced Linux Sound Architecture Driver Version k3.8.0-33-generic.
  ApportVersion: 2.0.1-0ubuntu17.6
  Architecture: amd64
   **** List of CAPTURE Hardware Devices ****
   card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
   /dev/snd/controlC0:  ubuntu     1776 F.... pulseaudio
  CRDA: Error: [Errno 2] No such file or directory
   Card hw:0 'PCH'/'HDA Intel PCH at 0xf3610000 irq 47'
     Mixer name	: 'Intel PantherPoint HDMI'
     Components	: 'HDA:10ec0269,17aa5002,00100202 HDA:80862806,80860101,00100000'
     Controls      : 29
     Simple ctrls  : 11
   Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw unknown'
     Mixer name	: 'ThinkPad EC (unknown)'
     Components	: ''
     Controls      : 1
     Simple ctrls  : 1
   Simple mixer control 'Console',0
     Capabilities: pswitch pswitch-joined penum
     Playback channels: Mono
     Mono: Playback [on]
  Date: Tue Nov 26 01:10:44 2013
  HibernationDevice: RESUME=UUID=0a4cd402-c938-4cc7-a55d-6230c539e25d
  InstallationMedia: Ubuntu 12.04.3 LTS "Precise Pangolin" - Release amd64 (20130820.1)
  MachineType: LENOVO 814TD01
  MarkForUpload: True
   PATH=(custom, no user)
   0 inteldrmfb
   1 nouveaufb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-33-generic root=UUID=6a396d09-0ad3-41a0-9d7d-18446b177e9d ro quiet splash vt.handoff=7
   linux-restricted-modules-3.8.0-33-generic N/A
   linux-backports-modules-3.8.0-33-generic  N/A
   linux-firmware                            1.79.7
  SourcePackage: linux-lts-raring
  StagingDrivers: keucr
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/10/2013
  dmi.bios.vendor: LENOVO
  dmi.bios.version: H5ET73WW(1.16)
  dmi.board.asset.tag: Not Available
  dmi.board.name: 814TD01
  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:bvrH5ET73WW(1.16):bd04/10/2013:svnLENOVO:pn814TD01:pvrLenovoV480:rvnLENOVO:rn814TD01:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 814TD01
  dmi.product.version: Lenovo V480
  dmi.sys.vendor: LENOVO

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