arandr | ARandR source code ; for issues and pull requests

I have similar setup and I got everything working what you might want if I understood you corretely.

If you setup everything right, then your loginmanager should always be displayed on the monitor which is active at boot and you can switch your monitors&sink with a simple keybind.

First, you can add a script to lightdm to config your monitors so that everything is displayed correctely. But be aware that a broken script can leed to the effect that your loginmanager won't be loaded correctly (blackscrren).

in /etc/lightdm/lightdm.conf you can define a script at #greeter-setup-script= . Simply uncomment the line and add the path to your script.

An easy way to config your monitors the way you want is to use arandr. Simply config your monitor the ways you want and save the setup. You will be saving an usual xrandr command, which can be used in your script.

Here is my script. It is very basic and actually only checks if a monitor of my desk is active. If so, it initialises the monitors of my desk. If not, it initialises my tv. It also sets the audio output I use with those monitors.

To get a list of all active monitors use this command:

xrandr --listactivemonitors | awk '!/Monitors/ {print $4}'

To get a list off all sinks(audio output) use this command:

pacmd list-sinks | grep -e 'name:' -e 'index:' | awk '{print $2}'| awk '{print substr($0, 2, length($0) - 2)}'

Now you can change my commands (sink and monitor names) with the onces you need. You can execute the script in the terminal so get feedback of the choosen sink and monitor (for testing). Don't forget to make your script executable else it won't work.

I got a similar script to manually change between my tv and my desk (mirroring scrrens, duplicate, tv-only, ect) It too changes the sink according to the selected monitors. As you are using polybar too, you might notice that I relaunch polybar with sh /home/lluks/.config/polybar/launch.sh This is the script. It ensures that my applets are displayed on the main monitor as poylbar can only display them on one monitor. This is archieved by using a 2 diffrent bars for poylbar. For this script to work, you need dmenu and rofi. If I remember corretely, you also need Font Awesome for the icons.

After two days of lightdm crash course, here is the answer, and it has nothing to do with Ryzen.

One file was missing from the lightdm configuration. This is an installation from scratch, so either it's missing from the Ubuntu Studio distribution, or maybe I unwittingly deleted it myself somehow.

The file is: /usr/share/lightdm/lightdm.conf.d/60-lightdm-gtk-greeter.conf:

I was able to solve this by disabling the vc4-fkms-v3d drivers. You can do this using the following steps:

1. Open you config file at /boot/config.txt
2. Using a #, comment out the line: vc4-fkms-v3d
3. Add the rotation to the config like:

• display_rotate=1 - for 90 degree rotation
• display_rotate=2 - for 180 degree rotation
• display_rotate=3 - for 270 degree rotation

1. Reboot

Your screen should now be rotated. Please note that this disables the vc4-fkms-v3d video card drivers which could have other unforeseen effects. Also keep in mind that this is the case for a RPi3.

Random drive-by idea that I am too lazy to test: