diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 45fd71d..83751dd 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -1306,6 +1306,15 @@ static int ahci_init_one (struct pci_dev
 		have_msi = 0;
 	}
 
+	{
+		u8 orig_pcs, pcs;
+		pci_read_config_byte(pdev, 0x92, &orig_pcs);
+		pci_write_config_byte(pdev, 0x92, 0xf);
+		pci_read_config_byte(pdev, 0x92, &pcs);
+		dev_printk(KERN_INFO, &pdev->dev, "pcs 0x%x->0x%x\n",
+			   orig_pcs, pcs);
+	}
+
 	probe_ent = kmalloc(sizeof(*probe_ent), GFP_KERNEL);
 	if (probe_ent == NULL) {
 		rc = -ENOMEM;