diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 559abe4ea4e9..c10c550da38b 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -411,7 +411,7 @@ static const char *sata_spd_string(unsigned int spd)
 
 static void ata_dev_disable(struct ata_port *ap, struct ata_device *dev)
 {
-	if (ata_dev_present(dev)) {
+	if (ata_dev_enabled(dev)) {
 		printk(KERN_WARNING "ata%u: dev %u disabled\n",
 		       ap->id, dev->devno);
 		dev->class++;
@@ -1222,7 +1222,7 @@ static int ata_dev_configure(struct ata_port *ap, struct ata_device *dev,
 	unsigned int xfer_mask;
 	int i, rc;
 
-	if (!ata_dev_present(dev)) {
+	if (!ata_dev_enabled(dev)) {
 		DPRINTK("ENTER/EXIT (host %u, dev %u) -- nodev\n",
 			ap->id, dev->devno);
 		return 0;
@@ -1401,7 +1401,7 @@ static int ata_bus_probe(struct ata_port *ap)
 
 		dev->class = classes[i];
 
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			continue;
 
 		WARN_ON(dev->id != NULL);
@@ -1565,7 +1565,7 @@ void sata_phy_reset(struct ata_port *ap)
 struct ata_device *ata_dev_pair(struct ata_port *ap, struct ata_device *adev)
 {
 	struct ata_device *pair = &ap->device[1 - adev->devno];
-	if (!ata_dev_present(pair))
+	if (!ata_dev_enabled(pair))
 		return NULL;
 	return pair;
 }
@@ -1778,7 +1778,7 @@ static int ata_host_set_pio(struct ata_port *ap)
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
 
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			continue;
 
 		if (!dev->pio_mode) {
@@ -1802,7 +1802,7 @@ static void ata_host_set_dma(struct ata_port *ap)
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
 
-		if (!ata_dev_present(dev) || !dev->dma_mode)
+		if (!ata_dev_enabled(dev) || !dev->dma_mode)
 			continue;
 
 		dev->xfer_mode = dev->dma_mode;
@@ -1830,7 +1830,7 @@ static void ata_set_mode(struct ata_port *ap)
 		struct ata_device *dev = &ap->device[i];
 		unsigned int pio_mask, dma_mask;
 
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			continue;
 
 		ata_dev_xfermask(ap, dev);
@@ -1858,7 +1858,7 @@ static void ata_set_mode(struct ata_port *ap)
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *dev = &ap->device[i];
 
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			continue;
 
 		rc = ata_dev_set_mode(ap, dev);
@@ -2550,7 +2550,7 @@ int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
 	u16 *id;
 	int rc;
 
-	if (!ata_dev_present(dev))
+	if (!ata_dev_enabled(dev))
 		return -ENODEV;
 
 	class = dev->class;
@@ -2679,7 +2679,7 @@ static void ata_dev_xfermask(struct ata_port *ap, struct ata_device *dev)
 	/* FIXME: Use port-wide xfermask for now */
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		struct ata_device *d = &ap->device[i];
-		if (!ata_dev_present(d))
+		if (!ata_dev_enabled(d))
 			continue;
 		xfer_mask &= ata_pack_xfermask(d->pio_mask, d->mwdma_mask,
 					       d->udma_mask);
@@ -4299,7 +4299,7 @@ int ata_device_resume(struct ata_port *ap, struct ata_device *dev)
 		ap->flags &= ~ATA_FLAG_SUSPENDED;
 		ata_set_mode(ap);
 	}
-	if (!ata_dev_present(dev))
+	if (!ata_dev_enabled(dev))
 		return 0;
 	if (dev->class == ATA_DEV_ATA)
 		ata_start_drive(ap, dev);
@@ -4317,7 +4317,7 @@ int ata_device_resume(struct ata_port *ap, struct ata_device *dev)
  */
 int ata_device_suspend(struct ata_port *ap, struct ata_device *dev, pm_message_t state)
 {
-	if (!ata_dev_present(dev))
+	if (!ata_dev_enabled(dev))
 		return 0;
 	if (dev->class == ATA_DEV_ATA)
 		ata_flush_cache(ap, dev);
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 53f5b0d9161c..c1a4b29a9ae1 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -2349,7 +2349,7 @@ ata_scsi_find_dev(struct ata_port *ap, const struct scsi_device *scsidev)
 		     (scsidev->lun != 0)))
 		return NULL;
 
-	if (unlikely(!ata_dev_present(dev)))
+	if (unlikely(!ata_dev_enabled(dev)))
 		return NULL;
 
 	if (!atapi_enabled || (ap->flags & ATA_FLAG_NO_ATAPI)) {
@@ -2743,7 +2743,7 @@ void ata_scsi_scan_host(struct ata_port *ap)
 	for (i = 0; i < ATA_MAX_DEVICES; i++) {
 		dev = &ap->device[i];
 
-		if (ata_dev_present(dev))
+		if (ata_dev_enabled(dev))
 			scsi_scan_target(&ap->host->shost_gendev, 0, i, 0, 0);
 	}
 }
diff --git a/drivers/scsi/sata_mv.c b/drivers/scsi/sata_mv.c
index fa901fd65085..0f7d334aadcc 100644
--- a/drivers/scsi/sata_mv.c
+++ b/drivers/scsi/sata_mv.c
@@ -1991,7 +1991,7 @@ comreset_retry:
 	tf.nsect = readb((void __iomem *) ap->ioaddr.nsect_addr);
 
 	dev->class = ata_dev_classify(&tf);
-	if (!ata_dev_present(dev)) {
+	if (!ata_dev_enabled(dev)) {
 		VPRINTK("Port disabled post-sig: No device present.\n");
 		ata_port_disable(ap);
 	}
diff --git a/drivers/scsi/sata_sil.c b/drivers/scsi/sata_sil.c
index 18c296c56899..d6c7086a5379 100644
--- a/drivers/scsi/sata_sil.c
+++ b/drivers/scsi/sata_sil.c
@@ -264,7 +264,7 @@ static void sil_post_set_mode (struct ata_port *ap)
 
 	for (i = 0; i < 2; i++) {
 		dev = &ap->device[i];
-		if (!ata_dev_present(dev))
+		if (!ata_dev_enabled(dev))
 			dev_mode[i] = 0;	/* PIO0/1/2 */
 		else if (dev->flags & ATA_DFLAG_PIO)
 			dev_mode[i] = 1;	/* PIO3/4 */
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 0d61357604d5..c6883ba8cba9 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -672,14 +672,24 @@ static inline unsigned int ata_tag_valid(unsigned int tag)
 	return (tag < ATA_MAX_QUEUE) ? 1 : 0;
 }
 
-static inline unsigned int ata_class_present(unsigned int class)
+static inline unsigned int ata_class_enabled(unsigned int class)
 {
 	return class == ATA_DEV_ATA || class == ATA_DEV_ATAPI;
 }
 
-static inline unsigned int ata_dev_present(const struct ata_device *dev)
+static inline unsigned int ata_class_disabled(unsigned int class)
 {
-	return ata_class_present(dev->class);
+	return class == ATA_DEV_ATA_UNSUP || class == ATA_DEV_ATAPI_UNSUP;
+}
+
+static inline unsigned int ata_dev_enabled(const struct ata_device *dev)
+{
+	return ata_class_enabled(dev->class);
+}
+
+static inline unsigned int ata_dev_disabled(const struct ata_device *dev)
+{
+	return ata_class_disabled(dev->class);
 }
 
 static inline u8 ata_chk_status(struct ata_port *ap)