GENET_TX_DMA_CONS_INDEX
printf("TX CIDX = %08x\n", RD4(sc, GENET_TX_DMA_CONS_INDEX(qid)));
WR4(sc, GENET_TX_DMA_CONS_INDEX(qid), 0);
cidx = RD4(sc, GENET_TX_DMA_CONS_INDEX(qid)) & 0xffff;