ata_pciide_dma_start
void ata_pciide_dma_start(ata_ctl_t *ata_ctlp, uchar_t direction);
ata_pciide_dma_start(ata_ctlp, PCIIDE_BMICX_RWCON_WRITE_TO_MEMORY);
ata_pciide_dma_start(ata_ctlp, PCIIDE_BMICX_RWCON_READ_FROM_MEMORY);
ata_pciide_dma_start(ata_ctlp, rd_wr);