ALC_DATA_FLOW_CTRL_REGISTER
ac_clr(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_CENTER_LFE);
ac_set(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_BACK_SURROUND);
ac_clr(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_BACK_SURROUND);
ac_set(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_SURROUND);
ac_clr(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_SURROUND);
ac_set(ac, ALC_DATA_FLOW_CTRL_REGISTER, ADFC_CENTER_LFE);