Revised HDMI Audio Patch For RadeonHD Driver
Christian's latest RadeonHD HDMI audio patch is over 60KB in size and is over 2,000 lines. As AMD hasn't released any documentation covering the registers for HDMI audio, he had reverse-engineered them. This most recent patch has a few fixes and enabled HDMI audio by default. The audio support though can be disabled from the xorg.conf.
This HDMI audio support has been tested and verified on the RV620, RV630, RV635, RV770, RS780, and M86 GPUs. Ideally we will see this patch merged into the xf86-video-radeonhd driver in the near future.