[alsa-devel] [PATCH v6 1/3] ASoC: Add initial support for multiple CPU DAIs

[Shreyas NC]

On Fri, Jun 22, 2018 at 10:13:28AM -0500, Pierre-Louis Bossart wrote:
> 
> >>>+static int snd_soc_init_single_cpu_dai(struct snd_soc_card *card,
> >>>+				   struct snd_soc_dai_link *dai_link)
> >>>+{
> >>>+	if (dai_link->cpu_name || dai_link->cpu_of_node ||
> >>>+					dai_link->cpu_dai_name) {
> >>>+		dai_link->num_cpu_dai = 1;
> >>>+		dai_link->cpu_dai = devm_kzalloc(card->dev,
> >>>+				sizeof(struct snd_soc_dai_link_component),
> >>>+				GFP_KERNEL);
> >>>+
> >>>+		if (!dai_link->cpu_dai)
> >>>+			return -ENOMEM;
> >>>+
> >>>+		dai_link->cpu_dai[0].name = dai_link->cpu_name;
> >>>+		dai_link->cpu_dai[0].of_node = dai_link->cpu_of_node;
> >>>+		dai_link->cpu_dai[0].dai_name = dai_link->cpu_dai_name;
> >>Question: is cpu_dai[i].of_node defined for i>0 in the multi cpu_dai case?
> >>
> >
> >Yes, it should be defined.
> 
> I have limited understanding of how cpu_of_node would be handled and if
> there is any guidance for DT folks on how to deal with multiple cpu_dais.
> 

>From what I could gather, it looks like we need not add additional code.
But, my understanding of DT is pretty limited as well. Vinod, Liam,  can you help us
here?

> >
> >>>@@ -1644,7 +1751,7 @@ int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
> >>>  	unsigned int dai_fmt)
> >>>  {
> >>>  	struct snd_soc_dai **codec_dais = rtd->codec_dais;
> >>>-	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
> >>>+	struct snd_soc_dai **cpu_dais = rtd->cpu_dais;
> >>>  	unsigned int i;
> >>>  	int ret;
> >>>@@ -1659,35 +1766,44 @@ int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
> >>>  		}
> >>>  	}
> >>>-	/* Flip the polarity for the "CPU" end of a CODEC<->CODEC link */
> >>why was this comment removed?
> >>
> >
> >Looks like I messed up resolving ocnflicts while rebase
> >
> >>>  	/* the component which has non_legacy_dai_naming is Codec */
> >>>-	if (cpu_dai->component->driver->non_legacy_dai_naming) {
> >>Not sure if the code refactoring below makes sense in a codec-codec link,
> >>you probably wouldn't have multiple cpu_dais then, would you?
> >
> >Yes, a valid point. You suggest to leave this piece of code as is ?
> 
> Not necessarily. I don't understand how the codec-codec and multi cpu_dais
> intersect, all I am asking for is a check if this change is needed or not.
> 

In soc_link_dai_widgets() which is called from probe_dai_links(),
we call out that we do not support multi cpu/codec for CODEC - CODEC link.
All the operation there are done only on single CPU DAI/Codec DAI.

But, in this function snd_soc_dai_set_fmt() is set on all Codec DAIs. So,
for sake of consistency we can do it for CPU DAIs too.

--Shreyas

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