[alsa-devel] [PATCH 05/11] ASoC: hdac_hdmi: Add multichannel support

[Takashi Iwai]

On Tue, 12 Apr 2016 15:36:33 +0200,
Subhransu S. Prusty wrote:
> 
> On Tue, Apr 12, 2016 at 07:25:33AM -0500, Pierre-Louis Bossart wrote:
> > 
> > -	/* Only stereo supported as of now */
> > -	cvt->params.channels_min = cvt->params.channels_max = 2;
> > +	chans = get_wcaps(hdac, cvt->nid);
> > +	chans = get_wcaps_channels(chans);
> > +
> > +	cvt->params.channels_min = 2;
> > +
> > +	if (chans <= 16) {
> > +		cvt->params.channels_max = chans;
> > +		if (chans > hdmi->chmap.channels_max)
> > +			hdmi->chmap.channels_max = chans;
> > +	}t
> > 
> > 
> > Are you sure about this? HDMI can only handle 8 channels in Layout
> > 2. There's no support for 16 ch.
> 
> I copied this change form patch_hdmi.c. From the git history I couldn't
> find why it is 16 ch. May be Takashi/Mengdong/Libin can confirm on this?

It's the max value the HD-audio widget capability bits may give.  We
don't check about the actual device limit there, only about the codec
chip capabilities.

Actually, with the recent code, the check is mostly useless, as it
can't be over 16.  You can apply it unconditionally.


Takashi