[alsa-devel] [RFT v3 3/3] ASoC: core: Add support for DAI multicodec

[Benoit Cousson]

Hi Lars,

I'm struggling a little bit to understand one of your comment :-)

On 26/04/2014 14:51, Lars-Peter Clausen wrote:
> On 04/24/2014 02:01 PM, Benoit Cousson wrote:
>> @@ -870,6 +876,10 @@ struct snd_soc_dai_link {
>>       const struct device_node *codec_of_node;
>>       /* You MUST specify the DAI name within the codec */
>>       const char *codec_dai_name;
>> +
>> +    struct snd_soc_dai_link_component *codecs;
> 
> Should probably be const

In fact, I don't think this is not possible, since this struct will be initialized at runtime in the legacy case when the regular codec struct is the one used by the driver.

[...]

>> @@ -1586,16 +1626,21 @@ static int soc_probe_link_dais(struct 
>> snd_soc_card *card, int num, int order)
>>                           codec2codec_close_delayed_work);
>>
>>               /* link the DAI widgets */
>> -            ret = soc_link_dai_widgets(card, dai_link,
>> -                    cpu_dai, codec_dai);
>> -            if (ret)
>> -                return ret;
>> +            for (i = 0; i < rtd->num_codecs; i++) {
>> +                ret = soc_link_dai_widgets(card, dai_link,
>> +                        cpu_dai, rtd->codec_dais[i]);
> 
> This will create a DAI link widget for each CODEC DAI. The DAI link 
> widget will configure the CPU and the CODEC DAI that are connected to 
> it. If there is one DAI link widget per CODEC DAI this means that the 
> CPU DAI will be connected to multiple DAI link widgets, which means it 
> will be configured once for each CODEC DAI (with possible conflicting 
> configurations).

I've got that point, but now I'm wondering what struct should be per codec_dai. Should we consider one source and several sinks to represent the multiple codecs?

> So there should only be one DAI link widget per DAI link, with the CPU 
> DAI on one side and the CODEC DAIs on the other side. Note that you'll 
> also need to re-work snd_soc_dai_link_event() to handle multiple 
> inputs/outputs. I'd factor that part out into a separate patch.

Here, I'm lost :-)

What struct should be made multiple in that case?

Should we consider that the following list can handle multiple sink/source?

	/* We only support a single source and sink, pick the first */
	source_p = list_first_entry(&w->sources, struct snd_soc_dapm_path,
				    list_sink);
	sink_p = list_first_entry(&w->sinks, struct snd_soc_dapm_path,
				  list_source);

[...]

Thanks,
Benoit

-- 
Benoît Cousson
BayLibre
Embedded Linux Technology Lab
www.baylibre.com