Brightness is low after resume from suspend, can't be increased

[Thomas Novin]

In Settings > Brightness & Lock the brightness is set to 100%. Also dim is not selected.

But, after resuming from suspend, the brightness is very low and I cannot increase it. Sliding that scaler does nothing and the same with the laptops FN-keys, they do nothing.

Reboot was required to fix the problem. First I tried to restart lightdm but could see after stopping it (sudo /etc/init.d/lightdm stop) that the terminal on vt1 was way to dim.

Edit: Last time this happened, I was able to get the brightness back by stopping lightdm and starting it again.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xorg 1:7.7+1ubuntu8
ProcVersionSignature: Ubuntu 3.13.0-19.40-generic 3.13.6
Uname: Linux 3.13.0-19-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Thu Mar 27 20:40:07 2014
DistUpgraded: Fresh install
DistroCodename: trusty
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:21cf]
InstallationDate: Installed on 2014-03-26 (1 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140325.1)
MachineType: LENOVO 42433ZG
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-19-generic root=UUID=c3c7f36f-ca42-443e-819f-5553fe3d040a ro quiet splash vt.handoff=7
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/26/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 8AET64WW (1.44 )
dmi.board.asset.tag: Not Available
dmi.board.name: 42433ZG
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:bvr8AET64WW(1.44):bd07/26/2013:svnLENOVO:pn42433ZG:pvrThinkPadT520:rvnLENOVO:rn42433ZG:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 42433ZG
dmi.product.version: ThinkPad T520
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.11+14.04.20140320.1-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.0-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.0-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.15.0-1ubuntu7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Thu Mar 27 13:48:07 2014
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 16561
 vendor LEN
xserver.version: 2:1.15.0-1ubuntu7

[Chris Wilson (ickle)]

Well that was unexpected. The ACPI backlight failing. </sarcasm>

[Thomas Novin (thomasn80)]

Any possible workaround?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Sebastian Gaul (n-admin-mgvmedia-com)]

Any workaround yet? This still happens regularly and is really annoying.

[Ryan (carbonfreeze)]

As a temporary work around, you can change virtual terminals (ctrl-alt F1 through F6) and adjust your brightness there if you have hardware keys, then switch back to your X session on VT7 with ctrl-alt F7. Still cant change brightness inside the X session with hardware keys or power manager, though.

[jeroenverh (jeroenverh2002)]

This worked for me (Intel card):

sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf

Add:
Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"
EndSection

Source:
http://news.softpedia.com/news/Ubuntu-14-04-and-Ubuntu-13-10-Still-Plagued-by-Brightness-Settings-Bug-Solution-420733.shtml

[Thomas Novin (thomasn80)]

Typical Ubuntu-style, lots of problem reports for this problem since 13.10 but no fixes :(

I think this happens more if you use two monitors and for example suspend the computer with an external monitor as primary display and secondary/laptop off and then wakeup from suspend without this external monitor.

[Charlesschaefer (charlesschaefer)]

I have the same problem.

One thing I've noticed is that opening the GUI in Settings > Brightness and setting Brightness to 100% changes the files /sys/class/backlight/acpi_video0/brightness and /sys/class/backlight/acpi_video0/actual_brightness, adding the value "15" (in my system).

This does nothing with brigthness.

But in my directory /sys/class/backlight/ there is another directory, called "intell_backlight", with the same files. I've changed the "brightness" file inside this directory and it changes the brightness of the screen.

My Solution is:

cat /sys/class/backlight/intel_backlight/max_brightness > /sys/class/backlight/intel_backlight/brightness

This restores the brightness to 100%.

[penalvch (penalvch)]

Original reporter -> https://launchpad.net/~konstigt-deactivatedaccount

[Erik Konstantopoulos (erikkon)]

#9 is a workaround not a solution.

[penalvch (penalvch)]

Erik Konstantopoulos, please see https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1298578/comments/10 .

[Paulo Marcel Coelho Aragão (marcelpaulo)]

This bug is still present in Xubuntu 18.04.

Workaround https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1298578/comments/7 does restore maximum brightness, but not the actual brightness level before suspending.

[penalvch (penalvch)]

Paulo Marcel Coelho Aragão, as this report is closed, if you would like your issue addressed, report your problem by using the computer the problem is reproducible with, and provide necessary debugging logs by filing a new report with Ubuntu via a terminal:
ubuntu-bug linux

Please feel free to subscribe me to it.