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[Launchpad Bug Tracker <677274@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/677274

Title:
  Brightness control on Lenovo Ideapad u450p behaves non-monotonically

Status in “linux” package in Ubuntu:
  Expired

Bug description:
  Expected: Keyboard keys change the brightness, where fn+down should decrease it, and fn+up should increase it. Maybe a nice applet showing what brightness is set.
  But, observed: The brightness alternates between very bright and very low. The applet shows up(in kde). To check whether this was a kde issue i used the command line, where the behavior is similar.

  root@rawls:/proc/acpi/video/VGA/LCD# cat brightness
  levels:  0 10 20 30 40 50 60 70 80 90 100
  current: 50

  and setting works with for example
  echo 70 > brightness

  which results in
  80: pretty dark
  0,20,40,60,100: slightly brighter, but still rather dark
  10,30,50,70,90: pretty bright
  which is not what one would,at least naively, expect.

  I tried some settings like 91, giving
  -bash: echo: write error: Invalid argument

  I tried the workaround from bug 513921, but after adding
  acpi_osi=linux and acpi_backlight=vendor I could not set the display
  brightness at all any more.

  ProblemType: Bug
  DistroRelease: Ubuntu 10.10
  Package: linux-image-2.6.35-22-generic 2.6.35-22.35
  Regression: No
  Reproducible: Yes
  ProcVersionSignature: Ubuntu 2.6.35-22.35-generic 2.6.35.4
  Uname: Linux 2.6.35-22-generic x86_64
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
  Architecture: amd64
  ArecordDevices:
   **** List of CAPTURE Hardware Devices ****
   card 0: Intel [HDA Intel], device 0: ALC272 Analog [ALC272 Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  goelzera   7763 F.... pulseaudio
  Card0.Amixer.info:
   Card hw:0 'Intel'/'HDA Intel at 0xf0400000 irq 46'
     Mixer name	: 'Realtek ALC272'
     Components	: 'HDA:10ec0272,17aac006,00100001'
     Controls      : 17
     Simple ctrls  : 10
  Card1.Amixer.info:
   Card hw:1 'HDMI'/'HDA ATI HDMI at 0xf0210000 irq 47'
     Mixer name	: 'ATI R6xx HDMI'
     Components	: 'HDA:1002aa01,00aa0100,00100100'
     Controls      : 4
     Simple ctrls  : 1
  Card1.Amixer.values:
   Simple mixer control 'IEC958',0
     Capabilities: pswitch pswitch-joined penum
     Playback channels: Mono
     Mono: Playback [off]
  Date: Fri Nov 19 00:52:44 2010
  HibernationDevice: RESUME=UUID=7a4abe7d-4147-48d0-8057-b1f964dc963b
  InstallationMedia: Kubuntu 10.10 "Maverick Meerkat" - Release Candidate amd64 (20100928.3)
  MachineType: LENOVO 3389
  ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.35-22-generic root=UUID=7965020f-a640-4958-8bea-09eb9aaa31a3 ro
  ProcEnviron:
   LANGUAGE=
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  RelatedPackageVersions: linux-firmware 1.38
  SourcePackage: linux
  WifiSyslog:

  dmi.bios.date: 01/20/2010
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 22CN35WW(V2.02)
  dmi.board.name: NITU1
  dmi.board.vendor: LENOVO
  dmi.board.version: REFERENCE
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: No Enclosure
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnLENOVO:bvr22CN35WW(V2.02):bd01/20/2010:svnLENOVO:pn3389:pvrLenovoIdeaPadU450p:rvnLENOVO:rnNITU1:rvrREFERENCE:cvnNoEnclosure:ct10:cvrN/A:
  dmi.product.name: 3389
  dmi.product.version: Lenovo IdeaPad U450p
  dmi.sys.vendor: LENOVO

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