Public bug reported:
After updating 14.04 systems to the Wily HWE stack, the notebooks often
fail to switch on external monitors when resuming (after a suspend) them
inside the docking station.
Here are the steps I did:
- dock the notebook in the docking station, with an external monitor connected
(they are then in a side-by-side mode, not clone mode)
- suspend the notebook (in this case I used the menu entry in the top right
Unity menu)
- resume the notebook
Expected results:
On resume the external monitor should be switched on and the display
configuration I had before suspending should be restored.
Actual result:
On resume the external monitor is not switched on, although the kernel
seems to think it is switched on (based on the xrandr output, which I
will also attach to this bugreport).
To get the monitor to switch on, I have to first switch it off, and then switch
is on again (using xrandr or the system-settings GUI, both work). After doing
that (e.g. xrandr --output DP2-2 --off followed by xrandr --output DP2-2 --mode
1920x1200) the displays are now in "clone" mode (I think it isn't really a
clone mode, but the displays don't have any offset to each other). The same
happens when using the system-settings GUI.
I have reproduced the above steps with drm.debug=0x1e. I hope this
helps.
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-generic-lts-wily 4.2.0.30.24
ProcVersionSignature: Ubuntu 4.2.0-30.36~14.04.1-generic 4.2.8-ckt3
Uname: Linux 4.2.0-30-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
Date: Thu Mar 3 17:11:52 2016
InstallationDate: Installed on 2016-03-03 (0 days ago)
InstallationMedia: Ubuntu 14.04.4 LTS "Trusty Tahr" - Release amd64 (20160217.1)
SourcePackage: linux-meta-lts-wily
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: linux-meta-lts-wily (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug trusty
** Attachment added: "xrandr output after resuming"
https://bugs.launchpad.net/bugs/1552824/+attachment/4587681/+files/xrandr_output_after_resume.txt
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https://bugs.launchpad.net/bugs/1552824
Title:
Lenovo T450s/T550 don't switch external monitor on after resuming in
docking station
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