Solution in comment #25 solves the problem for me in a Toshiba Portege
Z830.
Thanks!
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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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