[PATCH] libata-sff: Undo bug introduced with pci_iomap changes

If you have a controller with one channel disabled and unmapped the new
iomap code blindly tries to iomap unconfigured BARs. Later on the code
does the right thing and checks for unmapped bars but it is done in the
wrong order

Reorder the checks and make the iomap conditional

Tejun: I think the code below is now correct but would appreciate you
giving it a review.
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

drivers/ata/libata-sff.c

@@ -557,14 +557,32 @@ ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int
 	int i, p = 0;
 	void __iomem * const *iomap;
 
+	/* Discard disabled ports. Some controllers show their
+	   unused channels this way */
+	if (ata_resources_present(pdev, 0) == 0)
+		ports &= ~ATA_PORT_PRIMARY;
+	if (ata_resources_present(pdev, 1) == 0)
+		ports &= ~ATA_PORT_SECONDARY;
+
 	/* iomap BARs */
-	for (i = 0; i < 4; i++) {
+	if (ports & ATA_PORT_PRIMARY) {
+		for (i = 0; i <= 1; i++) {
+			if (pcim_iomap(pdev, i, 0) == NULL) {
+				dev_printk(KERN_ERR, &pdev->dev,
+					   "failed to iomap PCI BAR %d\n", i);
+				return NULL;
+			}
+		}
+	}
+	if (ports & ATA_PORT_SECONDARY) {
+		for (i = 2; i <= 3; i++) {
 			if (pcim_iomap(pdev, i, 0) == NULL) {
 				dev_printk(KERN_ERR, &pdev->dev,
 					   "failed to iomap PCI BAR %d\n", i);
 				return NULL;
 			}
 		}
+	}
 
 	pcim_iomap(pdev, 4, 0); /* may fail */
 	iomap = pcim_iomap_table(pdev);
@@ -577,13 +595,6 @@ ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int
 	probe_ent->irq = pdev->irq;
 	probe_ent->irq_flags = IRQF_SHARED;
 
-	/* Discard disabled ports. Some controllers show their
-	   unused channels this way */
-	if (ata_resources_present(pdev, 0) == 0)
-		ports &= ~ATA_PORT_PRIMARY;
-	if (ata_resources_present(pdev, 1) == 0)
-		ports &= ~ATA_PORT_SECONDARY;
-
 	if (ports & ATA_PORT_PRIMARY) {
 		probe_ent->port[p].cmd_addr = iomap[0];
 		probe_ent->port[p].altstatus_addr =