[PATCH] AHCI prefetch

[Jeff Garzik <jeff@garzik.org>]

This patch has been sitting in my tmp directory for ages.

We should probably turn this on, though the practical difference is
probably minimal.


diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 4e96ec5..973a794 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -64,8 +64,10 @@ enum {
 	AHCI_PORT_PRIV_DMA_SZ	= AHCI_CMD_SLOT_SZ + AHCI_CMD_TBL_SZ +
 				  AHCI_RX_FIS_SZ,
 	AHCI_IRQ_ON_SG		= (1 << 31),
+
 	AHCI_CMD_ATAPI		= (1 << 5),
 	AHCI_CMD_WRITE		= (1 << 6),
+	AHCI_CMD_PREFETCH	= (1 << 7),
 
 	RX_FIS_D2H_REG		= 0x40,	/* offset of D2H Register FIS data */
 
@@ -533,7 +535,7 @@ static void ahci_qc_prep(struct ata_queu
 	if (qc->tf.flags & ATA_TFLAG_WRITE)
 		opts |= AHCI_CMD_WRITE;
 	if (is_atapi_taskfile(&qc->tf))
-		opts |= AHCI_CMD_ATAPI;
+		opts |= AHCI_CMD_ATAPI | AHCI_CMD_PREFETCH;
 
 	pp->cmd_slot[0].opts = cpu_to_le32(opts);
 	pp->cmd_slot[0].status = 0;