To fix the BIOS loading problem, I patch the kernel Radeon driver to load the VBIOS from a file in case the other methods fail. I ended up just downloading a copy of the VBIOS for my card, but it's safer to dump it out from DOS.

Heres the patch (might need some changes for your kernel version): https://lists.freedesktop.org/archives/dri-devel/2014-November/072701.html