agg_wrcodec
ret = agg_wrcodec(ess, regno, data);
static int agg_wrcodec(struct agg_info*, int, u_int32_t);
agg_wrcodec(ess, AC97_REG_POWER, 0);
agg_wrcodec(ess, AC97_REG_POWER, 0x300);
agg_wrcodec(ess, AC97_REG_POWER, 0xdf00);