[PATCH] ASoC: snd_soc_dai_set_fmt add substream independence.

[Matt Flax]

On 31/3/20 10:13 pm, Mark Brown wrote:
> On Tue, Mar 31, 2020 at 06:40:26PM +1100, Matt Flax wrote:

>>> No, my advice is to go down that route if you are doing this.  I'm just
>>> not convinced that it's going to work reliably since this all sounds
>>> rather shaky.
>> OK - I can try to go down that route. However I would like to confirm that
>> having a codec to codec link doesn't require the original codec or CPU
>> drivers to have separate DAIs for playback and capture ? In my case both the
>> CPU and Codec drivers have single DAIs for both streams.
> OK, that probably won't help then :/


OK - well, the codec approach was worth a try. My concerns with the 
codec API is that it chews resources and clock cycles - if it is 
possible to work around it, then it is a good idea.

I feel that the best way to reduce resource consumption, complexity and 
overhead is to allow link formats to be defined based on the stream 
direction.

I can see why we would want different DAIs if the sample rate is 
asymmetric, however for word alignment perhaps we should let the stream 
direction seep into the snd_soc_dai opertions. These days CPU and Codec 
designers seem to treat both streams independently, which is why their 
registers can be independently configured.


thanks for the discussion

Matt