PDC_PKT_SUBMIT
writel(pp->pkt_dma, ata_mmio + PDC_PKT_SUBMIT);
readl(ata_mmio + PDC_PKT_SUBMIT); /* flush */
ap->ioaddr.cmd_addr + PDC_PKT_SUBMIT);
readl(ap->ioaddr.cmd_addr + PDC_PKT_SUBMIT);
ap->ioaddr.cmd_addr + PDC_PKT_SUBMIT);
readl(ap->ioaddr.cmd_addr + PDC_PKT_SUBMIT);