From 4cde32fc4b32e96a99063af3183acdfd54c563f0 Mon Sep 17 00:00:00 2001
From: Jeff Garzik <jeff@garzik.org>
Date: Mon, 24 Mar 2008 22:40:40 -0400
Subject: [PATCH] [libata] ahci: SB600 workaround is suspect... play it safe
 for now

At least one report claims that a878539ef994787c447a98c2e3ba0fe3dad984ec
failed to solve lockups, whereas the old limit-to-32-bit trick worked.

Restore the 32-bit limit, but also leave the 255-sector limit in place,
because we know that's needed as well.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
---
 drivers/ata/ahci.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 17ee6ed985d9..b1eb4e24c86a 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -433,6 +433,7 @@ static const struct ata_port_info ahci_port_info[] = {
 	/* board_ahci_sb600 */
 	{
 		AHCI_HFLAGS	(AHCI_HFLAG_IGN_SERR_INTERNAL |
+				 AHCI_HFLAG_32BIT_ONLY |
 				 AHCI_HFLAG_SECT255 | AHCI_HFLAG_NO_PMP),
 		.flags		= AHCI_FLAG_COMMON,
 		.link_flags	= AHCI_LFLAG_COMMON,
@@ -1217,8 +1218,11 @@ static void ahci_dev_config(struct ata_device *dev)
 {
 	struct ahci_host_priv *hpriv = dev->link->ap->host->private_data;
 
-	if (hpriv->flags & AHCI_HFLAG_SECT255)
+	if (hpriv->flags & AHCI_HFLAG_SECT255) {
 		dev->max_sectors = 255;
+		ata_dev_printk(dev, KERN_INFO,
+			       "SB600 AHCI: limiting to 255 sectors per cmd\n");
+	}
 }
 
 static unsigned int ahci_dev_classify(struct ata_port *ap)
-- 
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