diff --git a/drivers/scsi/ata_piix.c b/drivers/scsi/ata_piix.c
index bf41dd3a35d2..18b3542236d2 100644
--- a/drivers/scsi/ata_piix.c
+++ b/drivers/scsi/ata_piix.c
@@ -141,6 +141,7 @@ enum {
 
 struct piix_map_db {
 	const u32 mask;
+	const u32 port_enable;
 	const int map[][4];
 };
 
@@ -294,6 +295,7 @@ static const struct ata_port_operations piix_sata_ops = {
 
 static const struct piix_map_db ich5_map_db = {
 	.mask = 0x7,
+	.port_enable = 0x3,
 	.map = {
 		/* PM   PS   SM   SS       MAP  */
 		{  P0,  NA,  P1,  NA }, /* 000b */
@@ -309,6 +311,7 @@ static const struct piix_map_db ich5_map_db = {
 
 static const struct piix_map_db ich6_map_db = {
 	.mask = 0x3,
+	.port_enable = 0xf,
 	.map = {
 		/* PM   PS   SM   SS       MAP */
 		{  P0,  P2,  P1,  P3 }, /* 00b */
@@ -320,6 +323,7 @@ static const struct piix_map_db ich6_map_db = {
 
 static const struct piix_map_db ich6m_map_db = {
 	.mask = 0x3,
+	.port_enable = 0x5,
 	.map = {
 		/* PM   PS   SM   SS       MAP */
 		{  P0,  P2,  RV,  RV }, /* 00b */
@@ -519,44 +523,25 @@ static int piix_sata_prereset(struct ata_port *ap)
 	struct piix_host_priv *hpriv = ap->host_set->private_data;
 	const unsigned int *map = hpriv->map;
 	int base = 2 * ap->hard_port_no;
-	unsigned int present_mask = 0;
+	unsigned int present = 0;
 	int port, i;
-	u8 pcs;
+	u16 pcs;
 
-	pci_read_config_byte(pdev, ICH5_PCS, &pcs);
+	pci_read_config_word(pdev, ICH5_PCS, &pcs);
 	DPRINTK("ata%u: ENTER, pcs=0x%x base=%d\n", ap->id, pcs, base);
 
-	/* enable all ports on this ap and wait for them to settle */
-	for (i = 0; i < 2; i++) {
-		port = map[base + i];
-		if (port >= 0)
-			pcs |= 1 << port;
-	}
-
-	pci_write_config_byte(pdev, ICH5_PCS, pcs);
-	msleep(100);
-
-	/* let's see which devices are present */
-	pci_read_config_byte(pdev, ICH5_PCS, &pcs);
-
 	for (i = 0; i < 2; i++) {
 		port = map[base + i];
 		if (port < 0)
 			continue;
 		if (ap->flags & PIIX_FLAG_IGNORE_PCS || pcs & 1 << (4 + port))
-			present_mask |= 1 << i;
-		else
-			pcs &= ~(1 << port);
+			present = 1;
 	}
 
-	/* disable offline ports on non-AHCI controllers */
-	if (!(ap->flags & PIIX_FLAG_AHCI))
-		pci_write_config_byte(pdev, ICH5_PCS, pcs);
-
 	DPRINTK("ata%u: LEAVE, pcs=0x%x present_mask=0x%x\n",
 		ap->id, pcs, present_mask);
 
-	if (!present_mask) {
+	if (!present) {
 		ata_port_printk(ap, KERN_INFO, "SATA port has no device.\n");
 		ap->eh_context.i.action &= ~ATA_EH_RESET_MASK;
 		return 0;
@@ -770,6 +755,22 @@ static int __devinit piix_check_450nx_errata(struct pci_dev *ata_dev)
 	return no_piix_dma;
 }
 
+static void __devinit piix_init_pcs(struct pci_dev *pdev,
+				    const struct piix_map_db *map_db)
+{
+	u16 pcs, new_pcs;
+
+	pci_read_config_word(pdev, ICH5_PCS, &pcs);
+
+	new_pcs = pcs | map_db->port_enable;
+
+	if (new_pcs != pcs) {
+		DPRINTK("updating PCS from 0x%x to 0x%x\n", pcs, new_pcs);
+		pci_write_config_word(pdev, ICH5_PCS, new_pcs);
+		msleep(150);
+	}
+}
+
 static void __devinit piix_init_sata_map(struct pci_dev *pdev,
 					 struct ata_port_info *pinfo,
 					 const struct piix_map_db *map_db)
@@ -871,9 +872,11 @@ static int piix_init_one (struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 
 	/* Initialize SATA map */
-	if (host_flags & ATA_FLAG_SATA)
+	if (host_flags & ATA_FLAG_SATA) {
 		piix_init_sata_map(pdev, port_info,
 				   piix_map_db_table[ent->driver_data]);
+		piix_init_pcs(pdev, piix_map_db_table[ent->driver_data]);
+	}
 
 	/* On ICH5, some BIOSen disable the interrupt using the
 	 * PCI_COMMAND_INTX_DISABLE bit added in PCI 2.3.