Created attachment 141576 [details]
dmesg output on a broken system, using kernel 4.19_RC3
Multi-head on AMD Vega is not working on kernel 4.18 or 4.19RC, but works fine on 4.16
I'm stuck at kernel 4.16 with my hardware, current stable kernels leave me with just one display working.
Attaching dmesg output from 4.16, 4.18, and 4.19_RC3
Created attachment 141577 [details]
dmesg output from a working system, kernel 4.16
Created attachment 141578 [details]
dmesg output from broken system, kernel 4.18
Please post an Xorg log along with what distro/desktop environment you're using. It may also help if you can post another 4.19 dmesg log with drm.debug=6 in your bootline.
Uploading 4.19_RC5 dmesg w/ drm.debug=6 set, Xorg log
Also, here's more info about my setup:
-at this time there are no 3rd-party or non-foss additions
+Radeon RX Vega 54
+DVI port does not work
-Except on older 4.16 of course
Created attachment 141727 [details]
dmesg with drm.debug=6 set at boot time
Created attachment 141728 [details]
This has been resolved for me in the current 4.19 stable build. Thanks!