FXP_CB_COMMAND_NOP
txp[i].cb_command = FXP_CB_COMMAND_NOP;
txp->cb_command = FXP_CB_COMMAND_NOP | FXP_CB_COMMAND_S;
txp->cb_command = FXP_CB_COMMAND_NOP |
CSR_WRITE_1(sc, FXP_CSR_SCB_COMMAND, FXP_CB_COMMAND_NOP);