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,SNDRV_PCM_HW_PARAM_RATE,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 parameters.