Enable prefetching. This hints AHCI controller that it can prefetch
PRT entries and CDB (for PACKET commands). This is a hint. AHCI
controller is free to ignore it or prefetch regardless of this bit.
Note that prefetching bit should be turned off for NCQ commands or
FIS-based switching PM support.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
---
And this is the second version.
ahci.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 00dfdef..454a393 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -66,6 +66,7 @@ enum {
AHCI_IRQ_ON_SG = (1 << 31),
AHCI_CMD_ATAPI = (1 << 5),
AHCI_CMD_WRITE = (1 << 6),
+ AHCI_CMD_PREFETCH = (1 << 7),
AHCI_CMD_RESET = (1 << 8),
AHCI_CMD_CLR_BUSY = (1 << 10),
@@ -627,7 +628,7 @@ static void ahci_qc_prep(struct ata_queu
/*
* Fill in command slot information.
*/
- opts = cmd_fis_len | n_elem << 16;
+ opts = AHCI_CMD_PREFETCH | cmd_fis_len | n_elem << 16;
if (qc->tf.flags & ATA_TFLAG_WRITE)
opts |= AHCI_CMD_WRITE;
if (is_atapi)
-
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