[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>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index b4a0246..b0d0cc4 100644 (file)
--- 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 e54a5fd..d1af1db 100644 (file)
--- 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,