[PATCH v2 1/2] ata: libata-scsi: Fix initialization of device queue depth

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

For SATA devices supporting NCQ, drivers using libsas first initialize a
scsi device queue depth based on the controller and device capabilities,
leading to the scsi device queue_depth field being 32 (ATA maximum queue
depth) for most setup. However, if libata was loaded using the
force=[ID]]noncq argument, the default queue depth should be set to 1 to
reflect the fact that queuable commands will never be used. This is
consistent with manually setting a device queue depth to 1 through sysfs
as that disables NCQ use for the device.

Fix ata_scsi_dev_config() to honor the noncq parameter by sertting the
device queue depth to 1 for devices that do not have the ATA_DFLAG_NCQ
flag set.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
 drivers/ata/libata-scsi.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 29e2f55c6faa..ff9602a0e54e 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1055,6 +1055,7 @@ EXPORT_SYMBOL_GPL(ata_scsi_dma_need_drain);
 int ata_scsi_dev_config(struct scsi_device *sdev, struct ata_device *dev)
 {
 	struct request_queue *q = sdev->request_queue;
+	int depth = 1;
 
 	if (!ata_id_has_unload(dev->id))
 		dev->flags |= ATA_DFLAG_NO_UNLOAD;
@@ -1100,13 +1101,10 @@ int ata_scsi_dev_config(struct scsi_device *sdev, struct ata_device *dev)
 	if (dev->flags & ATA_DFLAG_AN)
 		set_bit(SDEV_EVT_MEDIA_CHANGE, sdev->supported_events);
 
-	if (dev->flags & ATA_DFLAG_NCQ) {
-		int depth;
-
+	if (dev->flags & ATA_DFLAG_NCQ)
 		depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
-		depth = min(ATA_MAX_QUEUE, depth);
-		scsi_change_queue_depth(sdev, depth);
-	}
+	depth = min(ATA_MAX_QUEUE, depth);
+	scsi_change_queue_depth(sdev, depth);
 
 	if (dev->flags & ATA_DFLAG_TRUSTED)
 		sdev->security_supported = 1;
-- 
2.37.3