[alsa-devel] [PATCH v6 3/3] ASoC: Add multiple CPU DAI support in DAPM

[Shreyas NC]

On Thu, Jun 21, 2018 at 09:55:54PM -0500, Pierre-Louis Bossart wrote:
> 
> 
> On 06/20/2018 05:54 AM, Shreyas NC wrote:
> >DAPM handles DAIs during soc_dapm_stream_event() and during addition
> >and creation of DAI widgets i.e., dapm_add_valid_dai_widget() and
> >dapm_connect_dai_link_widgets().
> can you split this patch in two, one where you add
> dapm_add_valid_dai_widget() and the second one where you add the multi-cpu
> stuff? the current diff format is really hard to read with the two changes
> lumped together.

As I had replied earlier, the change is really moving the same code from one
function to a new one. So, a patch split would mean we would have the same
duplicated code in one patch which surely is not desirable.

I just realized that in my earlier reply I had excluded the list and replied
only to you :)

> 
> >+	for (i = 0; i < rtd->num_codecs; i++) {
> >+		struct snd_soc_dai *codec_dai = rtd->codec_dais[i];
> >+
> >+		for (j = 0; j < rtd->num_cpu_dai; j++) {
> >+			cpu_dai = rtd->cpu_dais[j];
> >+
> >+			dapm_add_valid_dai_widget(card, rtd,
> >+						codec_dai, cpu_dai);
> 
> I didn't click on this earlier, but what makes you think all codec_dais are
> connected to all cpu_dais?

Yes, there need not be a M:N connectivity. But, how do you find that out ?

> That doesn't seem quite right.
> For the multi-codec case, all the codec_dais hang from a single cpu_dai.
> it's a stretch for me to have a full M:N connectivity. And that's clearly
> not the case for SoundWire stream in the multi-link case.

I mostly do not disagree with you here..

> Can't we use the dai_link information here to only connect cpu_ and
> codec_dais that are related?

Which DAI Link information are you referring to here ?
Other than the machine driver which sets the audio route, I am unable to
figure out how we will find out the connected cpu_dai and codec_dais at
ASoC core level.

May be I am missing something :(

--Shreyas

--