[gentoo-user] Strange behaviour disconnecting and reconnecting USB-C screen

[Andreas Fink <finkandreas@web.de>]

Hello,
I've got a new laptop and see a strange behaviour when disconnecting
and reconnecting my USB-C screen.
Here are the steps that I am doing. I have a dual screen setup with
xrandr, with my notebook screen being the primary screen and a second
large external screen connected via USB-C to my notebook directly.
Now I disconnect the USB-C cable and do not do anything software wise,
i.e. my X-Server is still pretending to run on two screens, I can move
the screen outside of my notebook screen (into the area where the
external screen).
Now I reconnect the USB-C cable but the screens stays blank (the the
screen it says "No USB Type-C connection from your computer"). The only
way to get a signal again is to first use xrandr to only use my
notebook screen, and at the exact time udev gets a DRM event, and
suddently my external monitor appears within xrandr as connected (I did
not touch the cable, I only ran an xrandr command to use only the
notebook screen). Right after the DRM event I can run the xrandr
command to use both screens, but it is annoying to degrade first to one
screen, because all windows are moved around and I do not end up with
the same window setup as before.

Using the same screen with the same experiment as described above but
with a different notebook the screen is able to pick up the signal
again, so it's not purely a problem with the external screen.
Any idea what is going on and how I can workaround it? I just want to
disconnect the cable and reconnect it without the need to switch any
xrandr setup.

Thanks for your ideas and help
Andreas