TXA_CTRL
CSR_WRITE_1(dev, MR_ADDR(pnum, TXA_CTRL),
CSR_WRITE_1(dev, MR_ADDR(pnum, TXA_CTRL), TXA_ENA_ARB);
CSR_WRITE_1(dev, MR_ADDR(pnum, TXA_CTRL), TXA_DIS_ARB);
CSR_WRITE_1(dev, MR_ADDR(i, TXA_CTRL), TXA_ENA_ARB);