libata: always use ata_qc_complete_multiple() for NCQ command completions

Currently, sata_fsl, mv and nv call ata_qc_complete() multiple times
from their interrupt handlers to indicate completion of NCQ commands.
This limits the visibility the libata core layer has into how commands
are being executed and completed, which is necessary to support IRQ
expecting in generic way.  libata already has an interface to complete
multiple commands at once - ata_qc_complete_multiple() which ahci and
sata_sil24 already use.

This patch updates the three drivers to use ata_qc_complete_multiple()
too and updates comments on ata_qc_complete[_multiple]() regarding
their usages with NCQ completions.  This change not only provides
better visibility into command execution to the core layer but also
simplifies low level drivers.

* sata_fsl: It already builds done_mask.  Conversion is straight
  forward.

* sata_mv: mv_process_crpb_response() no longer checks for illegal
  completions, it just returns whether the tag is completed or not.
  mv_process_crpb_entries() builds done_mask from it and passes it to
  ata_qc_complete_multiple() which will check for illegal completions.

* sata_nv adma: Similar to sata_mv.  nv_adma_check_cpb() now just
  returns the tag status and nv_adma_interrupt() builds done_mask from
  it and passes it to ata_qc_complete_multiple().

* sata_nv swncq: It already builds done_mask.  Drop unnecessary
  illegal transition checks and call ata_qc_complete_multiple().

In the long run, it might be a good idea to make ata_qc_complete()
whine if called when multiple NCQ commands are in flight.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ashish Kalra <ashish.kalra@freescale.com>
Cc: Saeed Bishara <saeed@marvell.com>
Cc: Mark Lord <liml@rtr.ca>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_nv.c

@@ -873,29 +873,11 @@ static int nv_adma_check_cpb(struct ata_port *ap, int cpb_num, int force_err)
 			ata_port_freeze(ap);
 		else
 			ata_port_abort(ap);
-		return 1;
+		return -1;
 	}
 
-	if (likely(flags & NV_CPB_RESP_DONE)) {
-		struct ata_queued_cmd *qc = ata_qc_from_tag(ap, cpb_num);
-		VPRINTK("CPB flags done, flags=0x%x\n", flags);
-		if (likely(qc)) {
-			DPRINTK("Completing qc from tag %d\n", cpb_num);
-			ata_qc_complete(qc);
-		} else {
-			struct ata_eh_info *ehi = &ap->link.eh_info;
-			/* Notifier bits set without a command may indicate the drive
-			   is misbehaving. Raise host state machine violation on this
-			   condition. */
-			ata_port_printk(ap, KERN_ERR,
-					"notifier for tag %d with no cmd?\n",
-					cpb_num);
-			ehi->err_mask |= AC_ERR_HSM;
-			ehi->action |= ATA_EH_RESET;
-			ata_port_freeze(ap);
-			return 1;
-		}
-	}
+	if (likely(flags & NV_CPB_RESP_DONE))
+		return 1;
 	return 0;
 }
 
@@ -1018,6 +1000,7 @@ static irqreturn_t nv_adma_interrupt(int irq, void *dev_instance)
 			      NV_ADMA_STAT_CPBERR |
 			      NV_ADMA_STAT_CMD_COMPLETE)) {
 			u32 check_commands = notifier_clears[i];
+			u32 done_mask = 0;
 			int pos, rc;
 
 			if (status & NV_ADMA_STAT_CPBERR) {
@@ -1034,10 +1017,13 @@ static irqreturn_t nv_adma_interrupt(int irq, void *dev_instance)
 				pos--;
 				rc = nv_adma_check_cpb(ap, pos,
 						notifier_error & (1 << pos));
-				if (unlikely(rc))
+				if (rc > 0)
+					done_mask |= 1 << pos;
+				else if (unlikely(rc < 0))
 					check_commands = 0;
 				check_commands &= ~(1 << pos);
 			}
+			ata_qc_complete_multiple(ap, ap->qc_active ^ done_mask);
 		}
 	}
 
@@ -2132,7 +2118,6 @@ static int nv_swncq_sdbfis(struct ata_port *ap)
 	struct ata_eh_info *ehi = &ap->link.eh_info;
 	u32 sactive;
 	u32 done_mask;
-	int i;
 	u8 host_stat;
 	u8 lack_dhfis = 0;
 
@@ -2152,27 +2137,11 @@ static int nv_swncq_sdbfis(struct ata_port *ap)
 	sactive = readl(pp->sactive_block);
 	done_mask = pp->qc_active ^ sactive;
 
-	if (unlikely(done_mask & sactive)) {
-		ata_ehi_clear_desc(ehi);
-		ata_ehi_push_desc(ehi, "illegal SWNCQ:qc_active transition"
-				  "(%08x->%08x)", pp->qc_active, sactive);
-		ehi->err_mask |= AC_ERR_HSM;
-		ehi->action |= ATA_EH_RESET;
-		return -EINVAL;
-	}
-	for (i = 0; i < ATA_MAX_QUEUE; i++) {
-		if (!(done_mask & (1 << i)))
-			continue;
-
-		qc = ata_qc_from_tag(ap, i);
-		if (qc) {
-			ata_qc_complete(qc);
-			pp->qc_active &= ~(1 << i);
-			pp->dhfis_bits &= ~(1 << i);
-			pp->dmafis_bits &= ~(1 << i);
-			pp->sdbfis_bits |= (1 << i);
-		}
-	}
+	pp->qc_active &= ~done_mask;
+	pp->dhfis_bits &= ~done_mask;
+	pp->dmafis_bits &= ~done_mask;
+	pp->sdbfis_bits |= done_mask;
+	ata_qc_complete_multiple(ap, ap->qc_active ^ done_mask);
 
 	if (!ap->qc_active) {
 		DPRINTK("over\n");