diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index df8f8a1a3a34..ef791ab8d9d1 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -330,7 +330,7 @@ struct ahci_port_priv {
 struct ahci_host_priv {
 	/* Input fields */
 	unsigned int		flags;		/* AHCI_HFLAG_* */
-	u32			mask_port_map;	/* mask out particular bits */
+	u32			mask_port_map;	/* Mask of valid ports */
 
 	void __iomem *		mmio;		/* bus-independent mem map */
 	u32			cap;		/* cap to use */
@@ -381,6 +381,17 @@ struct ahci_host_priv {
 						  int port);
 };
 
+/*
+ * Return true if a port should be ignored because it is excluded from
+ * the host port map.
+ */
+static inline bool ahci_ignore_port(struct ahci_host_priv *hpriv,
+				    unsigned int portid)
+{
+	return portid >= hpriv->nports ||
+		!(hpriv->mask_port_map & (1 << portid));
+}
+
 extern int ahci_ignore_sss;
 
 extern const struct attribute_group *ahci_shost_groups[];
diff --git a/drivers/ata/ahci_brcm.c b/drivers/ata/ahci_brcm.c
index 0411bad23147..481aab4d9b96 100644
--- a/drivers/ata/ahci_brcm.c
+++ b/drivers/ata/ahci_brcm.c
@@ -288,7 +288,7 @@ static unsigned int brcm_ahci_read_id(struct ata_device *dev,
 
 	/* Re-initialize and calibrate the PHY */
 	for (i = 0; i < hpriv->nports; i++) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		rc = phy_init(hpriv->phys[i]);
diff --git a/drivers/ata/ahci_ceva.c b/drivers/ata/ahci_ceva.c
index 6e115da23d3f..93275b1b4889 100644
--- a/drivers/ata/ahci_ceva.c
+++ b/drivers/ata/ahci_ceva.c
@@ -206,7 +206,7 @@ static int ceva_ahci_platform_enable_resources(struct ahci_host_priv *hpriv)
 		goto disable_clks;
 
 	for (i = 0; i < hpriv->nports; i++) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		rc = phy_init(hpriv->phys[i]);
@@ -218,7 +218,7 @@ static int ceva_ahci_platform_enable_resources(struct ahci_host_priv *hpriv)
 	ahci_platform_deassert_rsts(hpriv);
 
 	for (i = 0; i < hpriv->nports; i++) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		rc = phy_power_on(hpriv->phys[i]);
diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
index 2174a3e6e957..bfb103ca610d 100644
--- a/drivers/ata/libahci_platform.c
+++ b/drivers/ata/libahci_platform.c
@@ -49,7 +49,7 @@ int ahci_platform_enable_phys(struct ahci_host_priv *hpriv)
 	int rc, i;
 
 	for (i = 0; i < hpriv->nports; i++) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		rc = phy_init(hpriv->phys[i]);
@@ -73,7 +73,7 @@ int ahci_platform_enable_phys(struct ahci_host_priv *hpriv)
 
 disable_phys:
 	while (--i >= 0) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		phy_power_off(hpriv->phys[i]);
@@ -94,7 +94,7 @@ void ahci_platform_disable_phys(struct ahci_host_priv *hpriv)
 	int i;
 
 	for (i = 0; i < hpriv->nports; i++) {
-		if (!(hpriv->mask_port_map & (1 << i)))
+		if (ahci_ignore_port(hpriv, i))
 			continue;
 
 		phy_power_off(hpriv->phys[i]);