agg_rdcodec
ret = agg_rdcodec(ess, regno);
if (agg_rdcodec(ess, 0) == 0x80) {
static int agg_rdcodec(struct agg_info*, int);
if (agg_rdcodec(ess, 0) < 0) {
if ((agg_rdcodec(ess, AC97_REG_POWER) & 3) != 3)