1 files changed, 19 insertions, 16 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 27c8d56111c2..29e71bddd6ff 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -679,24 +679,20 @@ static void ahci_save_initial_config(struct pci_dev *pdev,
 
         /* cross check port_map and cap.n_ports */
         if (port_map) {
-                u32 tmp_port_map = port_map;
-                int n_ports = ahci_nr_ports(cap);
+                int map_ports = 0;
 
-                for (i = 0; i < AHCI_MAX_PORTS && n_ports; i++) {
-                        if (tmp_port_map & (1 << i)) {
-                                n_ports--;
-                                tmp_port_map &= ~(1 << i);
-                        }
-                }
+                for (i = 0; i < AHCI_MAX_PORTS; i++)
+                        if (port_map & (1 << i))
+                                map_ports++;
 
-                /* If n_ports and port_map are inconsistent, whine and
-                 * clear port_map and let it be generated from n_ports.
+                /* If PI has more ports than n_ports, whine, clear
+                 * port_map and let it be generated from n_ports.
                  */
-                if (n_ports || tmp_port_map) {
+                if (map_ports > ahci_nr_ports(cap)) {
                         dev_printk(KERN_WARNING, &pdev->dev,
-                                   "nr_ports (%u) and implemented port map "
-                                   "(0x%x) don't match, using nr_ports\n",
-                                   ahci_nr_ports(cap), port_map);
+                                   "implemented port map (0x%x) contains more "
+                                   "ports than nr_ports (%u), using nr_ports\n",
+                                   port_map, ahci_nr_ports(cap));
                         port_map = 0;
                 }
         }
@@ -2201,7 +2197,7 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         struct device *dev = &pdev->dev;
         struct ahci_host_priv *hpriv;
         struct ata_host *host;
-        int i, rc;
+        int n_ports, i, rc;
 
         VPRINTK("ENTER\n");
 
@@ -2255,7 +2251,14 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         if (hpriv->cap & HOST_CAP_PMP)
                 pi.flags |= ATA_FLAG_PMP;
 
-        host = ata_host_alloc_pinfo(&pdev->dev, ppi, fls(hpriv->port_map));
+        /* CAP.NP sometimes indicate the index of the last enabled
+         * port, at other times, that of the last possible port, so
+         * determining the maximum port number requires looking at
+         * both CAP.NP and port_map.
+         */
+        n_ports = max(ahci_nr_ports(hpriv->cap), fls(hpriv->port_map));
+
+        host = ata_host_alloc_pinfo(&pdev->dev, ppi, n_ports);
         if (!host)
                 return -ENOMEM;
         host->iomap = pcim_iomap_table(pdev);