I recently bought a new Lenovo ThinkPad T440p. This laptop comes with a Nvidia GeForce GT 730M/Intel HD 4600 hybrid graphics card. I am now trying to connect the laptop with the Lenovo ThinkPad Ultra Dock to two monitors via DisplayPort - but with no success so far.

If the laptop is connected to the docking station during the booting process, the login screen never appears. All monitors stay black but the integrated monitor is backlit. As soon I disconnect the laptop from the docking station, Xorg continues to load and the login screen appears.

If I connect the laptop to the docking station after logging in, the integrated display still works. But as soon as I try to activate one of the external displays in XFCE4 Display Settings the screen freezes. After disconnecting the laptop from the docking station it works again. Both situations can be reproduced with or without proprietary Nvidia drivers (319 and 331).

Here is the kernel output with additional DRM debug information:
http://pastebin.com/FMV9kj67

Here is the output of Xorg:
http://pastebin.com/W3U9T8pT

I also tried newer kernel versions (3.12 and 3.13) which didn't help either.

nvidia-settings and nvidia-xconfig do not recognize the external monitors when connected to the docking station. I have heard that in some ThinkPad models the DisplayPorts are wired to the Intel GPU directly. Does somebody have any information about this? Does it even matter?