ThinkPad Ultra Dock
Features:
- 1x VGA port
- 1x DVI-D port (single-link), 2x DisplayPort, 1x HDMI port (only 2 can be active)
- 3x USB 2.0 ports, one port supports always-on USB charging
- 3x USB 3.0 ports
- 10/100/1000 Gigabit Ethernet port
- Stereo/Microphone Combo Audio Port (4-pin TRRS connector with CTIA standard pinout, details: http://pinoutsguide.com/HeadsetsHeadphones/samsung_moment_pinout.shtml)
- Key lock (to secure system to the Dock)
- Kensington cable Lock Slot (to secure Dock to the desk)
- Ships with a 90W, 135W, or 170W power supply
The display ports are connected via an internal DisplayPort MST hub
The dock has upgradeable firmware. Lenovo has released one update which addresses an issue with Displayport output flickering or going blank.
- Information on the issue: https://support.lenovo.com/us/en/documents/ht081248
- Firmware download page: https://support.lenovo.com/us/en/documents/pd014572
Linux support for multiple screens
Linux does not yet offer explicit support for the DisplayPort MST hub built into this dock, so multi-screen support is not fully functional under Linux. A single screen works fine and is fully controllable, but multiple screens are handled by a some unconfigurable fallback mode, and appear a single display; they cannot be individually configured in terms of resolution, relative position etc.
On the ThinkPad X240, one way to use two external screens is to attach one to a dock port, and another to the laptop's own mini DisplayPort port.
Linux dock audio
When headphones are plugged into the docking station, the speakers are muted but no sound is played through the headphones. This is reportedly fixed in Linux kernel 3.16. With older kernels, such as 3.13 that is shipped with Ubuntu 14.04, a workaround is available. Details are here: https://bugzilla.redhat.com/show_bug.cgi?id=1101386#c10
The bug was reported for a T440s, but it probably applies to all Intel Haswell based ThinkPads. The magic values are slightly different for each model though.
