[alsa-devel] [RFC/RFT PATCH] ALSA: hda - hdmi: Add ATI/AMD multi-channel audio support

Anssi Hannula anssi.hannula at iki.fi
Sun Sep 22 23:14:11 CEST 2013

Just a small update on a few things.

22.09.2013 20:50, Anssi Hannula kirjoitti:
> Since there is no ELD support (unless out-of-band communication with the
> graphics driver is added so that they can provide it to us directly),
> ELD is currently emulated with only the basic information populated
> (speaker mask, SADs, connection type). There are some bits missing on
> the radeon driver side (the SADs etc are not populated) so currently
> the ELD emulation only works on fglrx. ELD emulation is not needed for
> multi-channel playback.

Actually, it seems this support is already there in radeon open-source
driver. It was added in 3.11 for some chips and 3.12 for others. I
haven't tested yet, though.

> HBR mode (needed for DTS-HD/TrueHD passthrough) is not working yet, and
> the released documentation does not mention it.

I'm hearing we may get HBR docs soon. If so, I'll update the patch
accordingly at that time.

> +				/* in paired mode we need to take into account
> +				 * the occupied channel pairs instead of just the
> +				 * channel count */
> +				for (c = 0; c < 8; c++) {
> +					if (cap->speakers[c] || cap->speakers[c+1])
> +						chanpairs++;
> +				}

s/c++/c += 2/

That part is still untested though.

Anssi Hannula

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