SND_CTL_SUBDEV_PCM 157 sound/core/pcm.c control->preferred_subdevice[SND_CTL_SUBDEV_PCM] = val; SND_CTL_SUBDEV_PCM 901 sound/core/pcm.c prefer_subdevice = snd_ctl_get_preferred_subdevice(card, SND_CTL_SUBDEV_PCM);