Index: sys/dev/ahci/ahci.c
===================================================================
--- sys/dev/ahci/ahci.c	(revision 218413)
+++ sys/dev/ahci/ahci.c	(working copy)
@@ -240,7 +240,7 @@ static struct {
 	{0x0abe10de, 0x00, "NVIDIA MCP79",	AHCI_Q_NOAA},
 	{0x0abf10de, 0x00, "NVIDIA MCP79",	AHCI_Q_NOAA},
 	{0x0d8410de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOAA},
-	{0x0d8510de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOAA},
+	{0x0d8510de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOFORCE|AHCI_Q_NOAA},
 	{0x0d8610de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOAA},
 	{0x0d8710de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOAA},
 	{0x0d8810de, 0x00, "NVIDIA MCP89",	AHCI_Q_NOAA},
Index: sys/dev/ata/chipsets/ata-nvidia.c
===================================================================
--- sys/dev/ata/chipsets/ata-nvidia.c	(revision 218413)
+++ sys/dev/ata/chipsets/ata-nvidia.c	(working copy)
@@ -178,10 +178,12 @@ ata_nvidia_probe(device_t dev)
 	return ENXIO;
 
     ata_set_desc(dev);
-    if (ctlr->chip->cfg1 & NVAHCI)
+    if ((ctlr->chip->chipid == ATA_NFORCE_MCP89_A1 &&
+	pci_get_subclass(dev) == PCIS_STORAGE_IDE) ||
+	(ctlr->chip->cfg1 & NVAHCI) == 0)
+	ctlr->chipinit = ata_nvidia_chipinit;
+    else
 	ctlr->chipinit = ata_ahci_chipinit;
-    else
-	ctlr->chipinit = ata_nvidia_chipinit;
     return (BUS_PROBE_DEFAULT);
 }