snd_pcm_hw_param_first —
int snd_pcm_hw_param_first
(struct snd_pcm_substream * pcm, struct snd_pcm_hw_params * params, snd_pcm_hw_param_t var, int * dir);
PCM instance
the hw_params instance
parameter to retrieve
pointer to the direction (-1,0,1) or NULL
Inside configuration space defined by PARAMS remove from PAR all values > minimum. Reduce configuration space accordingly. Return the minimum.