https://bugs.freedesktop.org/show_bug.cgi?id=70910
--- Comment #4 from Vadim Girlin ptpzz@yandex.ru --- Created attachment 94090 --> https://bugs.freedesktop.org/attachment.cgi?id=94090&action=edit xorg log when running w/o xorg.conf
If I remove xorg.conf (both cards still plugged in), I have one screen working (radeonsi) with correct colors.