[Intel 945GM/GMS] Plugging in external display results in garbled screen

[Dave Roberts]

When I plug in my external monitor, the image on the laptop (Dell Latitude D620) and on the monitor (Lenovo L220x) is corrupted. Mostly it goes black with some white diagonal blocks. See screenshot.

The problem occurs irrespective of whether Unity or Ubuntu Classic desktop is used. Some parts of the screen return to normal as they get refreshed, (e.g. network applet, system monitor applet etc), or the focus is given to an application.

Using the laptop's LCD switcher key sometimes has no effect and sometimes completely hangs the system to the point of a hard-reset is required.

Running the 'monitors' program, or xrandr shows both screens are detected correctly with the correct resolutions.

$ lspci -vvnn | grep 'VGA '
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller [8086:27a2] (rev 03) (prog-if 00 [VGA controller])

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-11-generic 2.6.38-11.48
ProcVersionSignature: Ubuntu 2.6.38-11.48-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: i386
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: dave 11930 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xdfebc000 irq 44'
   Mixer name : 'SigmaTel STAC9200'
   Components : 'HDA:83847690,102801c2,00102201 HDA:14f12bfa,14f100c3,00090000'
   Controls : 12
   Simple ctrls : 7
CheckboxSubmission: 9590d054d7732d6ca79b1e864619cea7
CheckboxSystem: d00f84de8a555815fa1c4660280da308
Date: Thu Sep 15 10:13:35 2011
HibernationDevice: RESUME=UUID=e58d09c1-6a8c-4a05-b00e-9d33465d2d38
MachineType: Dell Inc. Latitude D620
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   3.3V 32-bit PC Card
ProcEnviron:
 LANGUAGE=en_GB:en
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: root=UUID=9845e35f-8bdb-42c2-a6f8-a90922d5a40e ro quiet splash ipv6.disable=1
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-11-generic N/A
 linux-backports-modules-2.6.38-11-generic N/A
 linux-firmware 1.52
SourcePackage: linux
UpgradeStatus: Upgraded to natty on 2011-07-03 (73 days ago)
WpaSupplicantLog:

dmi.bios.date: 08/28/2006
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A04
dmi.board.name: 0TD761
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA04:bd08/28/2006:svnDellInc.:pnLatitudeD620:pvr:rvnDellInc.:rn0TD761:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Latitude D620
dmi.sys.vendor: Dell Inc.

[Dave Roberts (vpasvid)]

Forgot to mention that this is regression from previous version 10.10. In that version (and others before it) plugging in the external monitor worked as expected.

[Dave Roberts (vpasvid)]

Just tried the 11.10 beta-2 installation, and that exhibits the same problem.

Work is being done in this area though. The screen shot in https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/830949 is nearly identical to what I sometimes see.

[Dave Roberts (vpasvid)]

OK, progress of sorts.

If I log in using Ubuntu Classic (no effects), then plugging in the external monitors WORKS! I get an extended workspace.

However, previoiusly I used to use the Dell key (Fn-F8) to switch modes such that I had the external monitor only and the laptop display would be turned off. If I try that now, the external monitor displays a "signal out of range" error, and if I press the key a couple more times to get back to the laptop, the display comes back but scrolls horizontally at a pace too fast to see what's on the screen.

So there's some difference in the Ubuntu Classic options that is causing the main corruption problem. Perhaps this bug needs to be assigned to a different package other than the kernel.

[Chris Wilson (ickle)]

Now fixed through software fallbacks in libGL. >| (Who thought that was either a good idea?)