https://bugs.freedesktop.org/show_bug.cgi?id=103111
--- Comment #8 from Steve Falco stevenfalco@gmail.com --- As per the mailing list suggestions, I've built a kernel from the amd-staging-drm-next branch of the agd5f kernel tree.
While it gives me a usable gui, I also get "corrupted mapping in tail page" errors. Please see the dmesg attachment at https://bugs.freedesktop.org/attachment.cgi?id=134713 for the details.