[PATCH] sata_mv: three bug fixes

(1) A DMA transfer size of 0x10000 was not being written
as 0x0000 in the PRDs.  Fixed.

(1) The DEV_IRQ interrupt cause bit happens spuriously
during EDMA operation, and was not being ignored by the driver.
This led to various "drive busy" errors being reported,
with associated unpredictable behaviour.  Fixed.

(2) If a SATA or PCI interrupt was received with no outstanding
command, the interrupt handler still attempted to invoke
ata_qc_complete(), triggering assert()/BUG_ON() behaviour
elsewhere in libata.  Fixed.

The driver still has issues with confusion after error-recovery,
but should now  be reliable in the absence of drive errors.
I will be looking more into the error-handling bugs next.
Signed-Off-By: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/scsi/sata_mv.c

@@ -915,7 +915,7 @@ static void mv_fill_sg(struct ata_queued_cmd *qc)
 
 			pp->sg_tbl[i].addr = cpu_to_le32(addr & 0xffffffff);
 			pp->sg_tbl[i].addr_hi = cpu_to_le32((addr >> 16) >> 16);
-			pp->sg_tbl[i].flags_size = cpu_to_le32(len);
+			pp->sg_tbl[i].flags_size = cpu_to_le32(len & 0xffff);
 
 			sg_len -= len;
 			addr += len;
@@ -1187,7 +1187,6 @@ static void mv_host_intr(struct ata_host_set *host_set, u32 relevant,
 {
 	void __iomem *mmio = host_set->mmio_base;
 	void __iomem *hc_mmio = mv_hc_base(mmio, hc);
-	struct ata_port *ap;
 	struct ata_queued_cmd *qc;
 	u32 hc_irq_cause;
 	int shift, port, port0, hard_port, handled;
@@ -1210,25 +1209,31 @@ static void mv_host_intr(struct ata_host_set *host_set, u32 relevant,
 		hc,relevant,hc_irq_cause);
 
 	for (port = port0; port < port0 + MV_PORTS_PER_HC; port++) {
-		ap = host_set->ports[port];
+		struct ata_port *ap = host_set->ports[port];
+		struct mv_port_priv *pp = ap->private_data;
 		hard_port = port & MV_PORT_MASK;	/* range 0-3 */
 		handled = 0;	/* ensure ata_status is set if handled++ */
 
-		if ((CRPB_DMA_DONE << hard_port) & hc_irq_cause) {
-			/* new CRPB on the queue; just one at a time until NCQ
-			 */
-			ata_status = mv_get_crpb_status(ap);
-			handled++;
-		} else if ((DEV_IRQ << hard_port) & hc_irq_cause) {
-			/* received ATA IRQ; read the status reg to clear INTRQ
-			 */
-			ata_status = readb((void __iomem *)
+		/* Note that DEV_IRQ might happen spuriously during EDMA,
+		 * and should be ignored in such cases.  We could mask it,
+		 * but it's pretty rare and may not be worth the overhead.
+		 */ 
+		if (pp->pp_flags & MV_PP_FLAG_EDMA_EN) {
+			/* EDMA: check for response queue interrupt */
+			if ((CRPB_DMA_DONE << hard_port) & hc_irq_cause) {
+				ata_status = mv_get_crpb_status(ap);
+				handled = 1;
+			}
+		} else {
+			/* PIO: check for device (drive) interrupt */
+			if ((DEV_IRQ << hard_port) & hc_irq_cause) {
+				ata_status = readb((void __iomem *)
 					   ap->ioaddr.status_addr);
-			handled++;
+				handled = 1;
+			}
 		}
 
-		if (ap &&
-		    (ap->flags & (ATA_FLAG_PORT_DISABLED | ATA_FLAG_NOINTR)))
+		if (ap->flags & (ATA_FLAG_PORT_DISABLED | ATA_FLAG_NOINTR))
 			continue;
 
 		err_mask = ac_err_mask(ata_status);
@@ -1240,12 +1245,12 @@ static void mv_host_intr(struct ata_host_set *host_set, u32 relevant,
 		if ((PORT0_ERR << shift) & relevant) {
 			mv_err_intr(ap);
 			err_mask |= AC_ERR_OTHER;
-			handled++;
+			handled = 1;
 		}
 
-		if (handled && ap) {
+		if (handled) {
 			qc = ata_qc_from_tag(ap, ap->active_tag);
-			if (NULL != qc) {
+			if (qc && (qc->flags & ATA_QCFLAG_ACTIVE)) {
 				VPRINTK("port %u IRQ found for qc, "
 					"ata_status 0x%x\n", port,ata_status);
 				/* mark qc status appropriately */