https://bugs.freedesktop.org/show_bug.cgi?id=93715
--- Comment #5 from Dieter Nützel Dieter@nuetzel-hh.de --- Yes,
it works correctly with current mesa-git and a RX580 (Polaris 20), now.
Hello Gert, will try with my old 6670 HD (Turks XT) when I find more time to switch it back in.
But good progress so far.