Laptop screen dims on logout

[Jack Fromm]

After upgrading my laptop from Trusty to the Utopic final image, I noticed that when I logged out or switched users, the screen would dim. After logging back in, the brightness would not get restored. The Display Brightness slider in the Power Manager Plugin still showed full brightness, but it obviously was not. I had to click twice on the slider to restore the screen to full brightness.

I then did a clean install and had the same issue.

Similar to bug #1302025, but this is not due to inactivity.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: xfce4-power-manager 1.4.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-23.31-generic 3.16.4
Uname: Linux 3.16.0-23-generic x86_64
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: XFCE
Date: Wed Oct 22 21:09:36 2014
InstallationDate: Installed on 2014-10-23 (0 days ago)
InstallationMedia: Xubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
SourcePackage: xfce4-power-manager
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1384515

[Launchpad Janitor (janitor)]

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

[Simon Steinbeiß (ochosi)]

This is very likely not a bug in xfce4-power-manager, because when you log out/switch users /lock your session, you're going to a new VT, which means the default X11 settings are being used and xfce4-power-manager isn't running there (at least not at the greeter, it's only being started in the session).

Odd that you cannot change your brightness anymore within the session, I could also imagine that there are some driver issues. I presume this issue persists?

[Jack Fromm (jjfrv8)]

<<I presume this issue persists?>> Not sure. I have since gone back to Trusty on my laptop but I will try upgrading again and running the latest updates to see if the problem returns.

[Jack Fromm (jjfrv8)]

I upgraded my laptop again from Trusty to Utopic and the problem returned with the same symptoms. I then did a clean install of Vivid and had the same problem afterwards.

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

This appears to be a driver specific problem, similar to bug 1378353.

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

I suggest that you remove/disable xfce4-power-manager and test again.

Furthermore, we need details about your GPU + used driver. Please attach the output of "lspci -v" to this bug report.

[Jack Fromm (jjfrv8)]

Uninstalled xfce-power-manager. Screen still dims on logout and now I can't restore the brightness, even with the laptop function keys.
Attached output of lspci -v.

[Jack Fromm (jjfrv8)]

I re-read Simon's comment from 11-13 so I decided to try switching VTs. After logging out and getting to the greeter with a dimmed screen, if I switch to another VT and back to VT7, the brightness gets restored.

[Jack Fromm (jjfrv8)]

Per a suggestion on the xubuntu-devel IRC channel, I tested the intel xorg-edgers ppa driver -- to no avail.

Next suggestion was to try a later kernel. First, I did a fresh install of the current vivid daily image and confirmed that problem was still present. Then I installed the latest 3.17 kernel and that did seem to resolve the problem. So for the heck of it, I then installed the latest 3.19 RC and it's working okay with that one too.

[Thaddaeus Tintenfisch (thad-fisch-deactivatedaccount)]

Thank you for testing this.

[Jack Fromm (jjfrv8)]

Did a fresh install with the 20150110 daily - which has the 3.18.0-8 kernel - and the problem seems to be fixed!

[Jack Fromm (jjfrv8)]

Testing a clean install of the 14.04.2 image on this same laptop, I saw that the problem returned. Checked the kernel version and it was 3.16.0-30. The original Trusty release with the 3.13 kernel did not have the issue.

[Ang Bongsong (notinsideofhereiamnotinside)]

Can confirm that this is an issue under Xubuntu 14.04.2.

[Tim Schutte (kc8hr)]

I can also confirm this problem.

Lenovo X61 laptop

3.16.0-37-generic #51~14.04.1-Ubuntu SMP Wed May 6 15:23:14 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux