Index: linux-2.6.31-fast/drivers/ide/cmd64x.c
===================================================================
--- linux-2.6.31-fast.orig/drivers/ide/cmd64x.c	2009-10-21 06:08:42.000000000 +0200
+++ linux-2.6.31-fast/drivers/ide/cmd64x.c	2009-10-21 06:09:09.000000000 +0200
@@ -379,7 +379,8 @@ static const struct ide_port_info cmd64x
 		.enablebits	= {{0x00,0x00,0x00}, {0x51,0x08,0x08}},
 		.port_ops	= &cmd64x_port_ops,
 		.host_flags	= IDE_HFLAG_CLEAR_SIMPLEX |
-				  IDE_HFLAG_ABUSE_PREFETCH,
+				  IDE_HFLAG_ABUSE_PREFETCH |
+				  IDE_HFLAG_SERIALIZE,
 		.pio_mask	= ATA_PIO5,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= 0x00, /* no udma */
@@ -389,7 +390,8 @@ static const struct ide_port_info cmd64x
 		.init_chipset	= init_chipset_cmd64x,
 		.enablebits	= {{0x51,0x04,0x04}, {0x51,0x08,0x08}},
 		.port_ops	= &cmd648_port_ops,
-		.host_flags	= IDE_HFLAG_ABUSE_PREFETCH,
+		.host_flags	= IDE_HFLAG_ABUSE_PREFETCH |
+				  IDE_HFLAG_SERIALIZE,
 		.pio_mask	= ATA_PIO5,
 		.mwdma_mask	= ATA_MWDMA2,
 		.udma_mask	= ATA_UDMA2,