DP_SIDEBAND_MSG_DOWN_REQ_BASE
#define SIDE_BAND_MSG(address) (address >= DP_SIDEBAND_MSG_DOWN_REQ_BASE && address < DP_SINK_COUNT_ESI)
int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;