DisplayLink (as it's name might suggest) has nothing to do with DisplayPort. DisplayLink runs a compressed video stream over host USB to an external box (which decodes that compressed stream and pipes it to the dual DP ports on the box).
I read bad things about getting Thunderbolt working properly with Linux so bought a DisplayLink port extender (Lenovo) and it was an awful experience. Janky, didn't support the later kernel versions, didn't have a RPM or Fedora repo, crashed a few times a week. Awful.
Since then I've also bought a TB one and it works flawlessly. The DL one sits on my desk at work as a glorified charger now.
