when i try to start GNOME using an AMD RX 570 then it freezes directly at start.
But if i tell Xorg to use the scfb driver (Software Rendering) then it works.
Tested with xf86-video-amdgpu and the modesetting driver from package + using drm-kmod from ports with FreeBSD 12.2-STABLE r369250.
Its a x11-wm/mutter issue. When i try to use mutter standalone i have the same issue.
Have same problem on 13-Release and 14-current.
I manage to find workround for this problem .. by default xorg use DRI3 as default dri and disabling this and manualy specific to use DRI2 fix problem loading gnome3 and lags/freezes.
I can confirm this too, thank you!
This also works for Cinnamon.
Maybe this helps developer to track problem with amdgpu/gnome3 and DRI3.
The problem also seems to occur with x11-wm/enlightenment. If i want to use the hardware acceleration i must also use DRI2 otherwise i have only a black image with a cursor.
Could be similar to bug 251836 i.e., both iris and radeonsi use Gallium. Check if disabling GLX_EXT_buffer_age while keeping DRI3 enabled helps. For example, remove <device> and <application> guards in /usr/local/share/drirc.d/01-freebsd.conf then restart Xorg.
Tried .. no difference at all same problem when DRI3 on .