MCSX_PEX_TX_SLAVE_PORT_CONFIG
val = mcs_reg_read(mcs, MCSX_PEX_TX_SLAVE_PORT_CONFIG(req->port_id));
mcs_reg_write(mcs, MCSX_PEX_TX_SLAVE_PORT_CONFIG(req->port_id), val);
reg = MCSX_PEX_TX_SLAVE_PORT_CONFIG(req->port_id);