Comment 30 for bug 754799

Forwarding this bug from Ubuntu reporter Daniel Manrique:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/754799

[Problem]
xrandr cannot enable the external monitor. According to the log files it should be there, and the screen size is expanded as if it were there, but nothing displays on the monitor. At the point that the external monitor is hotplugged, dmesg shows this error:

[ 135.356761] [drm] GMBUS timed out, falling back to bit banging on pin 2 [i915 gmbus vga]

and this shows up in Xorg.0.log:

[ 531.748] (II) intel(0): Allocated new frame buffer 3072x1050 stride 12288, tile

Problem has been tested with the 11.04 kernel as well as 2.6.39-994.201104200727 and shows same behavior in both cases.

[Original Description]
Steps to reproduce:

1- Plug a monitor into the VGA output
2- Press the monitor switching key (fn-F5)

Expected result:
- Display appears on external monitor, either mirrored or as additional desktop space.

Actual result:
- The external monitor is shown in the Monitors panel, and gets correctly identified (I see Acer 19" or Dell 22", tested with two different screens)
- However, the monitor itself reports "no signal", and displays nothing.

I went as far back as Lucid and the problem still persists, so at least it doesn't appear to be a regression.

Oops, sorry, you're right about the hotkey, I'm repeating the test with xrandr this time.

I'm running the same experimental kernel:

http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-next-proposed/current/linux-image-2.6.39-994-generic_2.6.39-994.201104200727_amd64.deb

On booting I see the following references to the "GMBUS timed out, falling back to bit banging" message:

[ 14.327182] [drm] GMBUS timed out, falling back to bit banging on pin 3 [i915 gmbus panel]
[ 15.375376] [drm] GMBUS timed out, falling back to bit banging on pin 4 [i915 gmbus dpc]

I then tailed both /var/log/syslog and /var/log/Xorg.0.log, then plugged in the external display (no key presses, no xrandr yet). Here's what happens right when I plug it in (you're right, the GMBUS message appears right when I plug the external display):

==> /var/log/syslog <==
Apr 27 15:14:49 201002-5345 kernel: [ 530.567145] [drm] GMBUS timed out, falling back to bit banging on pin 2 [i915 gmbus vga]

==> /var/log/Xorg.0.log <==
[ 531.748] (II) intel(0): Allocated new frame buffer 3072x1050 stride 12288, tiled

I produced a dmesg file with this experimental kernel and the xdiagnose settings as described on #6. I do see some events when plugging in the external display and also when running xrandr --auto:

- Plugged in the external at [ 96.419325]
- xrandr --auto at [ 198.077408]

I'm attaching this new dmesg file as it might provide some information. Still, the problem persists and the external display shows nothing, even though it's being detected and used (terminal windows still appear in the external monitor, for instance, and I have to move them to the built-in to be able to use them).

DistroRelease: Ubuntu 11.04
Package: xorg 1:7.6+4ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-8.41-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,unitymtgrabhandles,scale,session,unityshell]
CompositorRunning: compiz
DRM.card0.DP.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.DP.2:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.HDMI.A.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.HDMI.A.2:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1366x768
 edid-base64:
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
Date: Fri Apr 8 12:43:18 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
GdmLog2:

GraphicsCard:
 Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 12) (prog-if 00 [VGA controller])
   Subsystem: Toshiba America Info Systems Device [1179:0002]
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta i386 (20110407.1)
MachineType: TOSHIBA TECRA A11
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-8-generic root=UUID=d3171176-99b3-404b-af92-0531218055e3 ro quiet splash vt.handoff=7
Renderer: Unknown
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/13/2009
dmi.bios.vendor: TOSHIBA
dmi.bios.version: Version 1.40
dmi.board.asset.tag: 0000000000
dmi.board.name: Portable PC
dmi.board.vendor: TOSHIBA
dmi.board.version: Version A0
dmi.chassis.asset.tag: 0000000000
dmi.chassis.type: 10
dmi.chassis.vendor: TOSHIBA
dmi.chassis.version: Version 1.0
dmi.modalias: dmi:bvnTOSHIBA:bvrVersion1.40:bd12/13/2009:svnTOSHIBA:pnTECRAA11:pvrPTSE0C-00N00N:rvnTOSHIBA:rnPortablePC:rvrVersionA0:cvnTOSHIBA:ct10:cvrVersion1.0:
dmi.product.name: TECRA A11
dmi.product.version: PTSE0C-00N00N
dmi.sys.vendor: TOSHIBA
version.compiz: compiz 1:0.9.4+bzr20110406-0ubuntu1
version.libdrm2: libdrm2 2.4.23-1ubuntu6
version.libgl1-mesa-dri: libgl1-mesa-dri 7.10.1-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.1-0ubuntu3
version.xserver-xorg: xserver-xorg 1:7.6+4ubuntu3
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu6
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu6

[lspci]
00:00.0 Host bridge [0600]: Intel Corporation Core Processor DRAM Controller [8086:0044] (rev 12)
     Subsystem: Toshiba America Info Systems Device [1179:0001]
00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 12) (prog-if 00 [VGA controller])
     Subsystem: Toshiba America Info Systems Device [1179:0002]