[alsa-devel] [PATCH 05/14] ASoC: Provide core support for symmetric sample rates

Peter Ujfalusi peter.ujfalusi at nokia.com
Wed Apr 15 08:31:46 CEST 2009

On Tuesday 14 April 2009 15:33:04 ext Mark Brown wrote:
> Many devices require symmetric configurations of capture and playback
> data formats, often due to shared clocking but sometimes also due to
> other shared playback and record configuration in the device. Start
> providing core support for this by allowing the DAIs or the machine
> to specify that the sample rates used should be kept symmetric.
> A flag symmetric_rates is provided in the snd_soc_dai and
> snd_soc_dai_link structures. If this is set in either of the DAIs or in
> the machine then a constraint will be applied when a stream is already
> open preventing any changes in sample rate.
> +
> +		ret = snd_pcm_hw_constraint_minmax(substream->runtime,
> +						   machine->rate,
> +						   machine->rate);

Would it make sense to add also the channel count and probably sample_bits as 
constraint as well here?
I think the symmetric means that you should not be able to change any of the 


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