What about symmetric_channels and symmetric_samplebits?

What about symmetric_channels and symmetric_samplebits?

[Nicolin Chen]

Hi all,

As far as I know, some SoCs can only work in mono or stereo mode at
one time. So if we let them capture a mono stream while playing a
stereo stream, there might be a problem occur to one of these two
streams: double-paced or slowed down.

I just want to ask: Is there any existing solution for the case?

In soc-pcm.c, we have soc_pcm_apply_symmetry() to solve unmatched
sample rates situation for simultaneous playback and capture. But
we don't have one for channels. Is that reasonable to add a similar
one for it?

Likewise, we can treat symmetric_rate as a solution for those SoCs
or CODECs which can not handle asymmetrical LRCLK. But it's also
impossible for them to handle asymmetrical BCLK. And accodring to
BCLK = LRCLK * channel number * slot size(fixed or sample bits),
sample bits might also be a problem if they are not using a fixed
slot size.

Thank you,
Nicolin Chen

Re: What about symmetric_channels and symmetric_samplebits?

[Mark Brown]

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On Mon, Nov 04, 2013 at 07:02:51PM +0800, Nicolin Chen wrote:

> In soc-pcm.c, we have soc_pcm_apply_symmetry() to solve unmatched
> sample rates situation for simultaneous playback and capture. But
> we don't have one for channels. Is that reasonable to add a similar
> one for it?

Yes.

> Likewise, we can treat symmetric_rate as a solution for those SoCs
> or CODECs which can not handle asymmetrical LRCLK. But it's also
> impossible for them to handle asymmetrical BCLK. And accodring to
> BCLK = LRCLK * channel number * slot size(fixed or sample bits),
> sample bits might also be a problem if they are not using a fixed
> slot size.

We could add core support for that constraint too, yes.

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