Based on reading the new and improved AMD drivers are supposed to handle MST.
I have a RX460 4GB based card (GC-RX460WF2OC-4GD) with 3 Dell U3014 monitors attached. (For the most part, this works well if I use each display from a separate output, Some of the issues I believe are KDE and not driver related.)
I tried going RX460 DP -> U3014 (mDP) DP-out -> U3014 (mDP) as the ONLY two monitors installed on the card. The cables are the DP1.2 'certified' cables shipped with the monitors and DP1.2 is enabled on the displays. (See linked photos.) The cables have worked in the past with a 7900 series card (on Debian no less, but more than a little unstable) and I have numerous instances of the cables supporting MST on various cards and IGP's. (Basically I am NOT concerned about the cabling OR my ability to properly configure my displays to handle MST.)
Ultimately I LIKE to switch over to MST for two of the displays ~IF~ the drivers support it. (Cable simplification is always a plus to me.)
Is this scenario supported (in 16.30.3-315407)? Does it require kernel arguments?
This is likely to become more important because the HDMI display is using a different color profile than the DP or DVI. Makes things UGLY when images are split across the displays. (This did NOT occur with the old 7900 card, using the Xorg drivers, EVEN with using two mDP and HDMI.)