[alsa-devel] radeon multi-channel lpcm

Pierre Ossman pierre-list at ossman.eu
Wed Sep 5 18:19:23 CEST 2012

Noone with any insight? I'm ready to do some leg work, but I couldn't
find anything in either the HDA specification, or the AMD
documentation. :/

On Fri, 31 Aug 2012 22:34:47 +0200
Pierre Ossman <pierre-list at ossman.eu> wrote:

> Hi,
> I figured I'd have a go at finishing up support for multi-channel lcpm
> over HDMI on radeon cards. I read a post from the AMD guys stating that
> the GPU portions were already in place, and it was the audio pieces
> that were missing. Unfortunately I was unable to figure out exactly what
> it is that remains to be done.
> I poked around in patch_hdmi.c, and concluded that the generic code is
> what's being used for modern radeon cards. The card exposes two widgets
> (and output widget and a pin complex). But both widgets indicate
> through their capability registers that they only support stereo.
> I don't know enough about HDA to have any clue where to go from here.
> Should the capability field be ignored for HDMI? Or does it need some
> coaxing to allow more than stereo? The ELD stuff isn't properly updated
> from the radeon driver, but the code seems to suggest it is just for
> hints, and not critical.
> Rgds

     -- Pierre Ossman

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