sata_mv: restructure mv_qc_issue

Rearrange logic in mv_qc_issue() to handle protocols
other than ATA_PROT_DMA, ATA_PROT_NCQ, and ATA_PROT_PIO.
This is in preparation for later enabling ATAPI support.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_mv.c

@@ -1565,14 +1565,26 @@ static void mv_qc_prep_iie(struct ata_queued_cmd *qc)
  */
 static unsigned int mv_qc_issue(struct ata_queued_cmd *qc)
 {
+	static int limit_warnings = 10;
 	struct ata_port *ap = qc->ap;
 	void __iomem *port_mmio = mv_ap_base(ap);
 	struct mv_port_priv *pp = ap->private_data;
 	u32 in_index;
+	unsigned int port_irqs = DONE_IRQ | ERR_IRQ;
 
-	if ((qc->tf.protocol != ATA_PROT_DMA) &&
-	    (qc->tf.protocol != ATA_PROT_NCQ)) {
-		static int limit_warnings = 10;
+	switch (qc->tf.protocol) {
+	case ATA_PROT_DMA:
+	case ATA_PROT_NCQ:
+		mv_start_edma(ap, port_mmio, pp, qc->tf.protocol);
+		pp->req_idx = (pp->req_idx + 1) & MV_MAX_Q_DEPTH_MASK;
+		in_index = pp->req_idx << EDMA_REQ_Q_PTR_SHIFT;
+
+		/* Write the request in pointer to kick the EDMA to life */
+		writelfl((pp->crqb_dma & EDMA_REQ_Q_BASE_LO_MASK) | in_index,
+					port_mmio + EDMA_REQ_Q_IN_PTR_OFS);
+		return 0;
+
+	case ATA_PROT_PIO:
 		/*
 		 * Errata SATA#16, SATA#24: warn if multiple DRQs expected.
 		 *
@@ -1590,27 +1602,22 @@ static unsigned int mv_qc_issue(struct ata_queued_cmd *qc)
 					": attempting PIO w/multiple DRQ: "
 					"this may fail due to h/w errata\n");
 		}
+		/* drop through */
+	case ATAPI_PROT_PIO:
+		port_irqs = ERR_IRQ;	/* leave DONE_IRQ masked for PIO */
+		/* drop through */
+	default:
 		/*
 		 * We're about to send a non-EDMA capable command to the
 		 * port.  Turn off EDMA so there won't be problems accessing
 		 * shadow block, etc registers.
 		 */
 		mv_stop_edma(ap);
-		mv_enable_port_irqs(ap, ERR_IRQ);
+		mv_edma_cfg(ap, 0, 0);
+		mv_clear_and_enable_port_irqs(ap, mv_ap_base(ap), port_irqs);
 		mv_pmp_select(ap, qc->dev->link->pmp);
 		return ata_sff_qc_issue(qc);
 	}
-
-	mv_start_edma(ap, port_mmio, pp, qc->tf.protocol);
-
-	pp->req_idx = (pp->req_idx + 1) & MV_MAX_Q_DEPTH_MASK;
-	in_index = pp->req_idx << EDMA_REQ_Q_PTR_SHIFT;
-
-	/* and write the request in pointer to kick the EDMA to life */
-	writelfl((pp->crqb_dma & EDMA_REQ_Q_BASE_LO_MASK) | in_index,
-		 port_mmio + EDMA_REQ_Q_IN_PTR_OFS);
-
-	return 0;
 }
 
 static struct ata_queued_cmd *mv_get_active_qc(struct ata_port *ap)