X recognises no screens when external connected

[Johan De Meersman]

When an external screen is connected through the dock (both displayport and displayport-to-dvi, on different docks), I get a message during startup that the X server has not found any screens.

Simply turning the screen off (not even disconnecting it) lets the system boot into the single laptop screen as per normal. When I turn on (or reconnect) the screen, it isn't recognised, and not even seen as far as syslog is concerned.

When not docked, the onboard displayport connection works as normal.

Yesterday everything was normal, the only relevant upgrade that happened was from kernel 3.16.0-38.52 to 3.19.0-32.37.

I've rebooted into the previous kernel, and that works normally - so I suspect a regression in the i915 driver or similar?

I'm running Linux Mint Xfce 17.3 64-bit, upgraded from 17.2 about a week ago.

I'm attaching the output of lshw and the apt history log; also dmesg for both kernel versions, as especially the i915-related lines are considerably different. I'm also noticing these lines in there, that aren't shown with the old kernel:

    [ 8.553727] [drm:gen8_irq_handler [i915_bpo]] *ERROR* The master control interrupt lied (SDE)!

I don't have an Xorg log for a failed session; I'll reboot later and make one; and then also verify wether the i915 modules are properly loaded - didn't think of checking that before.

[Johan De Meersman (vegivamp+launchpad)]

Here's the xorg logs from working and nonworking kernel. I also note that the 3.19 kernel doesn't load the i915 module, it loads i915_bpo instead. Manually loading i915 does not help; i915_bpo cannot be removed, even when no X processes are left.

I've edited my grub config to load the old kernel by default as a workaround; please tell me if there's anything else I can do to help debug the issue.

[Yorick Brunet (yorick-brunet-k)]

Same problem when I upgraded from 17.2 to 17.3.

I use a laptop (Thinkpad x250) on a docking station with external screen.

When I installed the new kernel 3.19.0-32, the X.org server could not find the screen anymore (see Xorg.log); even though the command line that appeared after X.org failed to start was displayed on both screens (laptop's and external). However, when using kernel 3.16.0-38, everything works fine.

I executed a "apt-get dist-upgrade" to be sure that everything has been updated, but this didn't when using kernel 3.19.0-32.

[Yorick Brunet (yorick-brunet-k)]

Add laptop hardware info

[Villosoph (armin-villiger)]

Same Problem here, Thinkpad Yoga S240

When I install the new kernel 3.19.0-32, the X.org server could not find the screen anymore (see Xorg.log);
The same happens with kernel 4.2.0-25. With kernel 3.13.0-24 everything works finde. Linux Mint 17.3.