Initiates the transfer for the specified group of subdevices. It is not required that all subdevices belong to one PCM device or one soundcard. Function may be called only when the driver is in SND_PCM_STATUS_PREPARED state (all subdevices must fulfil this condition), otherwise -EBADFD error is returned. Function returns zero if successful, otherwise it returns an error code.
If the operation was successful (zero is returned), then the driver state for all concerned subdevices is changed to SND_PCM_STATUS_RUNNING.