[fdo] xrandr output naming

[David Chen]

Hi,

On my Ubuntu device, I have observed that when connecting display port with MST enabled monitor, display output name in xrandr becomes something like DP-2-8, and there are more output interfaces listed in xrandr.  I am wondering how those names are defined.

Because of the naming change, it becomes difficult to create scripts to pe-configure display priority, resolution, position, and etc.
In my case, I have a device with Intel iGPU and AMD dGPU, and I want to pre-configure display priority when more than one monitor are connected to the system.  In my own environment, I use xorg.conf and udev rules for hotplug detect, and it works because those names don’t change.  However, if I bring the device to work, configuration needs to be changed again for different monitors.  Further more, except for MST monitors causing name difference, I see different names when primary GPU is changed from one to another.  I don’t know if there are better solutions for this, to have designated output names for display interfaces.

Thank you,

David