Last week new RadeonHD HDMI audio patches
were released by an independent developer that allows the integrated audio processor on ATI R600+ graphics cards to be used over HDMI using the open-source RadeonHD driver (xf86-video-radeonhd
). Today those patches have landed in the master branch of this X.Org driver. Some registers had to be reverse engineered because AMD hasn't released the documentation surrounding HDMI audio, but this support is known to work on at least several different card series. Check out the master branch of xf86-video-radeonhd for this committed work.