Re: [alsa-devel] [PATCH v2 3/5] ASoC: core: add support to snd_soc_dai_get_sdw_stream()

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It's been a while since this thread started, and I still don't
quite get the concepts or logic.

First, I don't understand what the problem with "aux" devices is.
All the SoundWire stuff is based on the concept of DAI, so I guess
I am

That is the actual problem! Some aux devices does not have dais.


Usually aux devices are used for things like analog amplifiers that
clearly don't have a digital interface, thus it really makes no sense
to have a DAI link connecting them. So I guess my question here
would be what is the thinking on making the "smart amplifier" dailess?
It feels like having a CODEC to CODEC DAI between the CODEC and
the AMP would be a more obvious way to connect the two devices
and would presumably avoid the issues being discussed around the
patch.

Ah, now I get it, I missed the point about not having DAIs for the amplifier.

I will second Charles' point, the code you have in the machine driver at [1] gets a SoundWire stream context from the SLIMbus codec dai. It's a bit odd to mix layers this way.


And if I look at the code below, taken from [1], if you have more than one codec, then your code looks problematic: data->sruntime would be overriden and you'd use the info from the last codec dai on the dailink...

case SLIMBUS_0_RX...SLIMBUS_6_TX:
  for (i = 0 ; i < dai_link->num_codecs; i++) {
    [snip]
    data->sruntime[cpu_dai->id] =
snd_soc_dai_get_sdw_stream(rtd->codec_dais[i], 0); << same destination for multiple codec_dais...

If you keep the amp dai-less, then the stream concept should be somehow allocated on the master (or machine) side and passed to the codec dais that are associated to the same 'stream'.
	

[1] https://git.linaro.org/people/srinivas.kandagatla/linux.git/tree/sound/soc/qcom/db845c.c?h=release/db845c/qcomlt-5.2




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