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[Bug 1178796] Re: [Asus UL80VT] Backlight control does not work, but there are entries in /sys/class/backlight


Guillaume Millet, this would not come from from the package acpi-
support, it's either a userspace or kernel issue. Hence, could you
please confirm this issue exists with the latest development release of
Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-
live/current/ . If the issue remains, could you please run the following
command in the development release from a Terminal
(Applications->Accessories->Terminal), as it will automatically gather
and attach updated debug information to this report:

apport-collect -p linux <replace-with-bug-number>

** Tags added: needs-upstream-testing

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  [Asus UL80VT] Backlight control does not work, but there are entries
  in /sys/class/backlight

Status in “linux” package in Ubuntu:

Bug description:
  Not working since the upgrade to Raring. Used to work on 12.10.

  Not working neither with linux-
  image-3.9.1-030901-generic_3.9.1-030901.201305080210 from

  Hotkeys are detected, showkey -s:
  0xe0 0x4c 0xe0 0xcc
  0xe0 0x54 0xe0 0xd4

  I also attach the results from tests described on

  Test with acpi_backlight=vendor:
  - on 3.8.0-20.31-generic, no change. But echo 8 > /sys/class/backlight/intel_backlight/brightness makes the screen dark, moreover /sys/class/backlight/intel_backlight/max_brightness = 2583660
  - on 3.9.1, no brightness change but the KDE notification pops up with only 3 levels (0, 53, 100%)

  Test with video.use_bios_initial_backlight=0:
  - on 3.8.0-20.31-generic, no change.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.04
  Package: linux-image-3.8.0-20-generic 3.8.0-20.31
  ProcVersionSignature: Ubuntu 3.8.0-20.31-generic 3.8.11
  Uname: Linux 3.8.0-20-generic x86_64
  ApportVersion: 2.9.2-0ubuntu8
  Architecture: amd64
   /dev/snd/controlC1:  guillaume   2490 F.... pulseaudio
   /dev/snd/controlC0:  guillaume   2490 F.... pulseaudio
  Date: Fri May 10 12:14:58 2013
  HibernationDevice: RESUME=/dev/sda6
  InstallationDate: Installed on 2010-01-19 (1207 days ago)
  InstallationMedia: Kubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
  MachineType: ASUSTeK Computer Inc. UL80VT
  MarkForUpload: True
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-20-generic root=UUID=d92f3a31-9e9c-4c19-98be-6fbc82629a36 ro video.use_bios_initial_backlight=0 quiet splash vt.handoff=7
   linux-restricted-modules-3.8.0-20-generic N/A
   linux-backports-modules-3.8.0-20-generic  N/A
   linux-firmware                            1.106
  SourcePackage: linux
  UpgradeStatus: Upgraded to raring on 2013-04-27 (12 days ago)
  dmi.bios.date: 01/17/2011
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: 214
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: UL80VT
  dmi.board.vendor: ASUSTeK Computer Inc.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: ATN12345678901234567
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK Computer Inc.
  dmi.chassis.version: 1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr214:bd01/17/2011:svnASUSTeKComputerInc.:pnUL80VT:pvr1.0:rvnASUSTeKComputerInc.:rnUL80VT:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
  dmi.product.name: UL80VT
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK Computer Inc.

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