I have a new 13" XPS (9370) running Ubuntu. I have been using an external monitor with a USB-C -> HDMI adapter. The other day, the adapter stopped working in one of the USB ports, but still worked fine on the other two ports. Then today, it stopped working on all three ports. The computer no longer recognizes that anything was connected, even though the cable is attached and the monitor is turned on. All three USB ports work with the computer's power adapter.
Any idea what could have caused this to stop working?
I opened up the BIOS and changed the Thunderbolt setting to "No Security" and now it seems to be working. Hopefully that did indeed fix the problem on an ongoing basis...
I'm running an XPS 9370 with the TB16 thunderbolt dock on Ubuntu 19.04. The thunderbolt devices work up to kernel version 5.0.0-15 and stopped working with 5.0.0-16.
For now I'm manually selecting kernel version 5.0.0-15 on each boot to mitigate.