Here's the relevant ALSA code: https://git.kernel.org/pub/scm/linux/kerne= l/git/torvalds/linux.git/tree/sound/pci/hda/hda_eld.c https://git.kernel.org/pub/scm/linux/ke= rnel/git/torvalds/linux.git/tree/sound/pci/hda/patch_hdmi.c The display driver parses the audio capabilities of the monitor and then pa= sses that information to the audio driver via a shared structure called the ELD.= =20 AMD hardware doeswn't use an ELD directly since display audio support on AMD hardware pre-dated ELD. Instead, the display driver writes fills in the au= dio descriptors from the monitor into registers that are shared between the aud= io hardware and the display hardware. The audio driver then parses these registers and generated and ELD which is used by the audio driver to determ= ine what audio modes are supported by the display. See snd_hdmi_get_eld_ati().= =20 See patch_atihdmi() for how the streams are set up on the audio side.