ICHD_PCM2IN
return snd_intel8x0_pcm_open(substream, &chip->ichd[ICHD_PCM2IN]);
chip->ichd[ICHD_PCM2IN].substream = NULL;
.ac97_idx = ICHD_PCM2IN,
chip->ichd[ICHD_PCM2IN].pcm = &pbus->pcms[4];
struct ac97_pcm *pcm = chip->ichd[ICHD_PCM2IN].pcm;