Comment # 9 on bug 73848 from Marti Raudsepp

(In reply to comment #7)
> Does manually disabling audio on 3.13 break things?  E.g., set
> radeon.audio=0 on the kernel command line in grub.

No, that doesn't seem to change anything. GDM still works, no errors in logs.
alsamixer still displays an "HDA ATI HDMI" card.

Am I doing it wrong?
% cat /proc/cmdline
initrd=\initramfs-linux.img root=UUID=f76fdeca-b4f3-49f7-891e-910c1c17b1f8 rw
radeon.audio=0