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[Bug 1214148] Re: [Toshiba Portege Z935-ST4N03] Intel video: Display backlight cannot be changed

 

Thanks Carlos Reig!

Either I didn't see that last time I visited the Debugging page, or it
has been added recently.

Anyway, the solution in comment #25 worked for me.

So... it looks like something like this needs to get into Ubuntu by
default for this laptop. I have no idea how that would be accomplished,
but that is indeed the solution.

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https://bugs.launchpad.net/bugs/1214148

Title:
  [Toshiba Portege Z935-ST4N03] Intel video: Display backlight cannot be
  changed

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  On my Toshiba Portege Z935-ST4N03 laptop, the display hotkeys and
  display brightness settings do not work at all.

  Symptoms:
  1. When I use Fn F6 or Fn F7, I get a pop-up window that shows a light bulb and a slider, and the slider goes obediently up and down as I press F6/7. However, the brightness of the screen does not change as the slider indicator changes.
  2. If I go into the Power Manager and set the display brightness to dim after a few seconds has passed, it doesn't dim.

  So it seems to me that the hotkeys are being recognized as a method to
  change the display brightness, but that the operating system is unable
  to change the hardware's actual screen brightness... I don't think
  it's a hotkey problem per se.

  I read through https://wiki.ubuntu.com/Kernel/Debugging/Backlight and
  I think I have the problem defined as:

  Backlight control does not work, but there are entries in
  /sys/class/backlight.

  Although I do not seem to have the Brightness applet on my system (I
  am running XFCE, so maybe that is why), but the Power Manager's
  brightness control is definitely not working.

  This is a recent install of Ubuntu, on a newly purchased laptop, so I
  have no idea whether it was working in previous versions of Ubuntu,
  kernels, etc. Sorry.

  I used the "ubuntu-bug" utility to report this bug, so I am not sure
  what else you need... but I am starting by attaching the Xorg log, and
  will attach the lspci output and other information shortly. I am also
  going to follow the rest of the debugging steps on the Backlight
  debugging page and attach the output as separate comments on this
  report.

  $ lsb_release -rd
  Description:	Ubuntu 13.04
  Release:	13.04

  $apt-cache policy xorg
  xorg:
    Installed: 1:7.7+1ubuntu4
    Candidate: 1:7.7+1ubuntu4
    Version table:
   *** 1:7.7+1ubuntu4 0
          500 http://us.archive.ubuntu.com/ubuntu/ raring/main amd64 Packages
          100 /var/lib/dpkg/status

  ProblemType: Bug
  DistroRelease: Ubuntu 13.04
  Package: xorg 1:7.7+1ubuntu4
  ProcVersionSignature: Ubuntu 3.8.0-27.40-generic 3.8.13.4
  Uname: Linux 3.8.0-27-generic x86_64
  ApportVersion: 2.9.2-0ubuntu8.1
  Architecture: amd64
  Date: Mon Aug 19 14:01:34 2013
  InstallationDate: Installed on 2013-06-17 (62 days ago)
  InstallationMedia: Xubuntu 13.04 "Raring Ringtail" - Release amd64 (20130423.1)
  MarkForUpload: True
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: xorg
  Symptom: display
  UpgradeStatus: No upgrade log present (probably fresh install)

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