Karmic: External display through display port not working

[Cima]

Binary package hint: xorg

External display using the digital Display Port (and adapter to DVI) is not working. VGA output is instead working fine. Display Port output worked once, apparently for no reason (just unplugging and plugging again for a few times), but never worked any more. Booting with/without the external display connected (or on/off) does not make any difference.
The laptop screen is detected as DP1, but no external display is found. The output of xrandr -q follows:

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
VGA1 disconnected (normal left inverted right x axis y axis)
DP1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
   1366x768 60.1*+ 40.1
HDMI1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
DP4 disconnected (normal left inverted right x axis y axis)

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: xorg 1:7.5+5ubuntu1
Uname: Linux 2.6.35-02063504-generic i686
Architecture: i386
Date: Mon Sep 13 10:06:35 2010
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
ProcEnviron:
 LANGUAGE=it_IT:en_GB:en
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/zsh
SourcePackage: xorg
Symptom: display
system:
 distro: Ubuntu
 codename: lucid
 architecture: i686
 kernel: 2.6.35-02063504-generic

[Cima (andrea-cimatoribus)]

Ok, the solution is the following, as crazy at it may sound. I have to plug in and turn on the external display while the laptop is showing the bios options. If I plug it later, or before switching it on, it won't be detected!

[komputes (komputes)]

Thank you for reporting this bug and helping to make Ubuntu better. Can you please provide the output of the following command:

$ lspci -nnk | grep -A2 VGA

It should say that the video card is using nvidia (closed source, proprietary binary) and not nouveau (free open source). Most advanced features (such as display port) do not work properly under noueau driver. To install the nvidia driver simply go to System > Administration > Hardware Drivers and enables the proposed/suggested driver for your video card.

[Cima (andrea-cimatoribus)]

Hi,
my video card is the intel integrated:

lspci -nnk | grep -A2 VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 12)
 Kernel driver in use: i915
 Kernel modules: i915

so I don't think your comment applies. And no proprietary drivers are available, anyway. Please note that I am using the latest 2.6.35 kernel from Maverick.

[Fabián Rodríguez (magicfab)]

If you still have this problem with Lucid or Maverick, please file a new bug by using:
ubuntu-bug xserver-xorg-video-intel