[PATCH] libata: turn off NCQ if queue depth is adjusted to 1

Turn off NCQ if queue depth is adjusted to 1.

Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 12 insertions, 1 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b4a0246506ef..b0d0cc41f3e8 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -889,6 +889,7 @@ int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
 {
         struct ata_port *ap = ata_shost_to_port(sdev->host);
         struct ata_device *dev;
+        unsigned long flags;
         int max_depth;
 
         if (queue_depth < 1)
@@ -904,6 +905,14 @@ int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
                 queue_depth = max_depth;
 
         scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
+
+        spin_lock_irqsave(ap->lock, flags);
+        if (queue_depth > 1)
+                dev->flags &= ~ATA_DFLAG_NCQ_OFF;
+        else
+                dev->flags |= ATA_DFLAG_NCQ_OFF;
+        spin_unlock_irqrestore(ap->lock, flags);
+
         return queue_depth;
 }
 
@@ -1293,7 +1302,8 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, const u8 *scsicm
                  */
                 goto nothing_to_do;
 
-        if ((dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ)) == ATA_DFLAG_NCQ) {
+        if ((dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ_OFF |
+                           ATA_DFLAG_NCQ)) == ATA_DFLAG_NCQ) {
                 /* yay, NCQ */
                 if (!lba_48_ok(block, n_block))
                         goto out_of_range;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index e54a5fd6a41e..d1af1dbeaeb4 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -143,6 +143,7 @@ enum {
         ATA_DFLAG_CFG_MASK      = (1 << 8) - 1,
 
         ATA_DFLAG_PIO           = (1 << 8), /* device limited to PIO mode */
+        ATA_DFLAG_NCQ_OFF       = (1 << 9), /* devied limited to non-NCQ mode */
         ATA_DFLAG_SUSPENDED     = (1 << 10), /* device suspended */
         ATA_DFLAG_INIT_MASK     = (1 << 16) - 1,