Thunderbolt docking and display issues

Asked by RRBell on 2018-08-01


Dell XPS 9570 i9 32GB RAM, GeForce GTX 1050 Ti (with Max-Q Design)

Dell Thunderbolt TB16 180W

External Monitor:
BenQ 32" LED PD3200U

Ubuntu 18.04
nVidia driver (390.48)

When booting with a thunderbolt docking station connected, the "Dell Thunderbolt Dock" is sometimes authorized and other times not. (Seems to be random, with a higher percentage of "not being authorized" than being authorized). (But every time the screens flicker)

When booting - even if the dock is not authorized, the screen connected to the docking station appears correctly as I have configured it. With correct display being the primary display. But when I am forced to authorize the thunderbolt docking the entire screen flickers and Display settings are forgotten/ignored. Then I get a "Single Display" with the internal screen. When trying to select "Join Displays" again the screen flickers and sometimes works and other times not. (Mostly it works). And requires several attempts to make my external secondary screen as the primary screen and to the right of my internal screen.

What I expected to happen:
After approving a thunderbolt dock - I assumed it would be approved next time I boot and keep all settings.
I would also assume less flickering while booting.

Since this is my workstation - I don't dare to do much experimentation like removing / inserting the usb-c cable, hibernating the laptop, etc. When it works - I try to not do anything that can make it not work ;-)

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RRBell (rrbell) said : #1

This also happened today when I installed the Opera snap-install via "Ubuntu Software": the display mode swapped to "Single Display" mode, with only the primary (the external monitor) showing the wallpaper and other related information. It was still possible to move windows onto the laptop screen - but when moving a window around the background was not refreshed leaving "window-marks" as a trail after the window being moved around. And Display Mode used several attempts to convert to "Join Displays" again. (Popped back to Single Display almost every time)

Launchpad Janitor (janitor) said : #2

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