Comment 18 for bug 754799

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).