Comment 15 for bug 1376771

response from linux-fbdev:

Hi Dennis,

Only drivers for DisplayLink's USB 2.0 generation chips (DL-1x5) are available and in kernel. That Dell dock is using the newer DL-3x00 chips. There's no way to get the graphics portion working for Linux on that.

Part of the reason is even for USB 2.0 graphics devices where the driver is in kernel, getting anything working is very distro and component-version dependent. You'll see a few success stories if you search around, but they're fleeting. In short, it's not for any normal user. For the longer story (if you have a USB 2.0 generation device), see http://plugable.com/2014/03/06/displaylink-usb-2-0-graphics-adapters-on-linux-2014-edition
.
By the way, programmatically you can tell the difference between the DL-1x5 chips and the newer ones by these portions of the USB descriptors:
  idVendor 0x17e9 DisplayLink [this is the vendor ID for all DisplayLink chips, regardless of brand of product they're used in]
  Configuration Descriptor:
    Interface Descriptor:
      bInterfaceClass 255 Vendor Specific Class
      bInterfaceSubClass 0
      bInterfaceProtocol 3 [DL-3x0 chips with in-kernel support have bInterfaceProtocol=3. Later protocols are not supported]

This is how they're distinguished in uldfb (the fbdev driver I helped with) and udl (the DRM driver David Airlie created).

Sorry for the bad news,
Bernie