diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 622350d9b2e3..0cd3ad497136 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1712,6 +1712,8 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 	else
 		tag = 0;
 
+	if (test_and_set_bit(tag, &ap->qc_allocated))
+		BUG();
 	qc = __ata_qc_from_tag(ap, tag);
 
 	qc->tag = tag;
@@ -4562,6 +4564,37 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
 #endif /* __BIG_ENDIAN */
 }
 
+/**
+ *	ata_qc_new - Request an available ATA command, for queueing
+ *	@ap: Port associated with device @dev
+ *	@dev: Device from whom we request an available command structure
+ *
+ *	LOCKING:
+ *	None.
+ */
+
+static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
+{
+	struct ata_queued_cmd *qc = NULL;
+	unsigned int i;
+
+	/* no command while frozen */
+	if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
+		return NULL;
+
+	/* the last tag is reserved for internal command. */
+	for (i = 0; i < ATA_MAX_QUEUE - 1; i++)
+		if (!test_and_set_bit(i, &ap->qc_allocated)) {
+			qc = __ata_qc_from_tag(ap, i);
+			break;
+		}
+
+	if (qc)
+		qc->tag = i;
+
+	return qc;
+}
+
 /**
  *	ata_qc_new_init - Request an available ATA command, and initialize it
  *	@dev: Device from whom we request an available command structure
@@ -4571,20 +4604,16 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
  *	None.
  */
 
-struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag)
+struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev)
 {
 	struct ata_port *ap = dev->link->ap;
 	struct ata_queued_cmd *qc;
 
-	if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
-		return NULL;
-
-	qc = __ata_qc_from_tag(ap, tag);
+	qc = ata_qc_new(ap);
 	if (qc) {
 		qc->scsicmd = NULL;
 		qc->ap = ap;
 		qc->dev = dev;
-		qc->tag = tag;
 
 		ata_qc_reinit(qc);
 	}
@@ -4592,6 +4621,31 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag)
 	return qc;
 }
 
+/**
+ *	ata_qc_free - free unused ata_queued_cmd
+ *	@qc: Command to complete
+ *
+ *	Designed to free unused ata_queued_cmd object
+ *	in case something prevents using it.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_qc_free(struct ata_queued_cmd *qc)
+{
+	struct ata_port *ap = qc->ap;
+	unsigned int tag;
+
+	WARN_ON(qc == NULL);	/* ata_qc_from_tag _might_ return NULL */
+
+	qc->flags = 0;
+	tag = qc->tag;
+	if (likely(ata_tag_valid(tag))) {
+		qc->tag = ATA_TAG_POISON;
+		clear_bit(tag, &ap->qc_allocated);
+	}
+}
+
 void __ata_qc_complete(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 3fa75eac135d..47c7afcb36f2 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -709,11 +709,7 @@ static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
 {
 	struct ata_queued_cmd *qc;
 
-	if (cmd->request->tag != -1)
-		qc = ata_qc_new_init(dev, cmd->request->tag);
-	else
-		qc = ata_qc_new_init(dev, 0);
-
+	qc = ata_qc_new_init(dev);
 	if (qc) {
 		qc->scsicmd = cmd;
 		qc->scsidone = done;
@@ -1108,17 +1104,7 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
 
 		depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
 		depth = min(ATA_MAX_QUEUE - 1, depth);
-
-		/*
-		 * If this device is behind a port multiplier, we have
-		 * to share the tag map between all devices on that PMP.
-		 * Set up the shared tag map here and we get automatic.
-		 */
-		if (dev->link->ap->pmp_link)
-			scsi_init_shared_tag_map(sdev->host, ATA_MAX_QUEUE - 1);
-
-		scsi_set_tag_type(sdev, MSG_SIMPLE_TAG);
-		scsi_activate_tcq(sdev, depth);
+		scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
 	}
 
 	return 0;
@@ -1958,11 +1944,6 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf)
 		hdr[1] |= (1 << 7);
 
 	memcpy(rbuf, hdr, sizeof(hdr));
-
-	/* if ncq, set tags supported */
-	if (ata_id_has_ncq(args->id))
-		rbuf[7] |= (1 << 1);
-
 	memcpy(&rbuf[8], "ATA     ", 8);
 	ata_id_string(args->id, &rbuf[16], ATA_ID_PROD, 16);
 	ata_id_string(args->id, &rbuf[32], ATA_ID_FW_REV, 4);
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index d3831d39bdaa..fe2839e58774 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -74,7 +74,7 @@ extern struct ata_link *ata_dev_phys_link(struct ata_device *dev);
 extern void ata_force_cbl(struct ata_port *ap);
 extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
 extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
-extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, int tag);
+extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev);
 extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
 			   u64 block, u32 n_block, unsigned int tf_flags,
 			   unsigned int tag);
@@ -103,6 +103,7 @@ extern int ata_dev_configure(struct ata_device *dev);
 extern int sata_down_spd_limit(struct ata_link *link);
 extern int ata_down_xfermask_limit(struct ata_device *dev, unsigned int sel);
 extern void ata_sg_clean(struct ata_queued_cmd *qc);
+extern void ata_qc_free(struct ata_queued_cmd *qc);
 extern void ata_qc_issue(struct ata_queued_cmd *qc);
 extern void __ata_qc_complete(struct ata_queued_cmd *qc);
 extern int atapi_check_dma(struct ata_queued_cmd *qc);
@@ -118,22 +119,6 @@ extern struct ata_port *ata_port_alloc(struct ata_host *host);
 extern void ata_dev_enable_pm(struct ata_device *dev, enum link_pm policy);
 extern void ata_lpm_schedule(struct ata_port *ap, enum link_pm);
 
-/**
- *	ata_qc_free - free unused ata_queued_cmd
- *	@qc: Command to complete
- *
- *	Designed to free unused ata_queued_cmd object
- *	in case something prevents using it.
- *
- *	LOCKING:
- *	spin_lock_irqsave(host lock)
- */
-static inline void ata_qc_free(struct ata_queued_cmd *qc)
-{
-	qc->flags = 0;
-	qc->tag = ATA_TAG_POISON;
-}
-
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI
 extern void ata_acpi_associate_sata_port(struct ata_port *ap);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index c7665a4134c5..59b0f1c807b5 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -698,6 +698,7 @@ struct ata_port {
 	unsigned int		cbl;	/* cable type; ATA_CBL_xxx */
 
 	struct ata_queued_cmd	qcmd[ATA_MAX_QUEUE];
+	unsigned long		qc_allocated;
 	unsigned int		qc_active;
 	int			nr_active_links; /* #links with active qcs */