1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 588ab2fd59e7..cb7853b7335d 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -193,6 +193,8 @@ enum {
                                           ATA_FLAG_ACPI_SATA | ATA_FLAG_AN |
                                           ATA_FLAG_IPM,
         AHCI_LFLAG_COMMON               = ATA_LFLAG_SKIP_D2H_BSY,
+
+        ICH_MAP                         = 0x90, /* ICH MAP register */
 };
 
 struct ahci_cmd_hdr {
@@ -2273,6 +2275,22 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         if (rc)
                 return rc;
 
+        if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
+            (pdev->device == 0x2652 || pdev->device == 0x2653)) {
+                u8 map;
+
+                /* ICH6s share the same PCI ID for both piix and ahci
+                 * modes.  Enabling ahci mode while MAP indicates
+                 * combined mode is a bad idea.  Yield to ata_piix.
+                 */
+                pci_read_config_byte(pdev, ICH_MAP, &map);
+                if (map & 0x3) {
+                        dev_printk(KERN_INFO, &pdev->dev, "controller is in "
+                                   "combined mode, can't enable AHCI mode\n");
+                        return -ENODEV;
+                }
+        }
+
         hpriv = devm_kzalloc(dev, sizeof(*hpriv), GFP_KERNEL);
         if (!hpriv)
                 return -ENOMEM;