display to external screen from Thinkpad L590 through Thinkpad Hybrid USB-C dock on Ubuntu 20.04

I am trying to:

• use a Thinkpad L590 running Ubuntu 20.04
• connected to a Thinkpad Hybrid USB-C USB-A dock
• to display to an external monitor connected by HDMI to the dock

I cannot get it to work (the screen detects no signal). Of course if I connect the screen directly to the laptop it works.

I tried to disable secure boot as some discussions suggested that online, with no effect.

Any idea?

Edit 1:

If I plug in the screen (which has a USB-C output) directly to the USB-C of the laptop, it works too. The problem is to get it to work through the USB-C of the dock, so that I have only 1 cable going from the laptop to the dock.

Edit 2:

The Thinkpad L590 belongs to the series L and, therefore, it has only USB C, no thunderbolt. Can this be the explanation?

Solution 1:

Better late than never but I thought I'd share my success with the same issues I've been having. Prior to this, at best I could only get 1 of my external monitors to work via the dock using various suggestions I found elsewhere.

1. Install the latest DisplayLink Driver for Ubuntu: https://www.synaptics.com/products/displaylink-graphics/downloads/ubuntu

2. Be sure to follow the steps here closely: https://support.displaylink.com/knowledgebase/articles/1944022-how-to-install-displaylink-software-on-ubuntu-20-0

3. Follow this steps outlined here: https://gist.github.com/bitsurgeon/b0f4440984c9e60dcd8fe8bbc346c029

4. This step in particular enabled all my external monitors to work:

   xrandr --setprovideroutputsource modesetting NVIDIA-0 && xrandr --auto
   

My setup:

• Lenovo P53 Quadro T2000
• Ubuntu 20.04 LTS
• ThinkPad Hybrid USB-C with USB-A Dock
• 2x External monitors connected via HDMI on the Dock