Re: [PATCH v3 2/3] ASoC: soc-pcm: Indicate warning if CPU / Codec availability mismatch

[Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>]

On 5/21/24 10:12, Mark Brown wrote:
> On Tue, May 21, 2024 at 08:43:09AM -0500, Pierre-Louis Bossart wrote:
> 
>> allow me to give you another counter example, beyond the AEC reference I
>> mentioned earlier. It's not uncommon for CPU DAIs to have loopback
>> capabilities, which are used for tests on boards where the codec has no
>> capture capabilities. I think it's a feature that needs to be allowed,
>> not a 'wrong setting'.
> 
> This is something we could do properly if we had full digital routing
> rather than bolting things on the side of the CPU<->CODEC model - having
> these things where we have to take a CODEC into account even though
> we're not actually using it is one of the big issues with DPCM.

No disagreement here, these echo references and loopbacks are ugly to
support with the dependency between playback and capture directions that
isn't well handled, e.g. if someone starts to capture before playback
started.

For now we're kind of stuck, what I would suggest is just to remove the
extra check that both CPU and codec dai can support a direction, and
move on with the other cleanups suggested by Morimoto-san.