Lockout as in no systemd services working, can't ssh into it or switch tty/vt and getting a blank screen. Here is the systemd journal log when booting with the default radeon.dpm=1: http://pastebin.com/raw.php?i=SRpX7QLK If by microcode you mean the early KMS/initramfs, yes, it is installed correctly and works with radeon.dpm=0.