mix_getdevs
p = mix_getdevs(sc->sm);
mix_setdevs(m, mix_getdevs(m) | (1 << SOUND_MIXER_SYNTH));
mix_setdevs(m, mix_getdevs(m) & ~(1 << SOUND_MIXER_SYNTH));
p->inputs = pdev->si_drv1? mix_getdevs(pdev->si_drv1) : 0;
*(int *)arg = mix_getdevs(m);
v = mix_getdevs(m);
u_int32_t mix_getdevs(struct snd_mixer *m);