hpsa: avoid unnecessary readl on every command submission
for controllers which support either of the ioaccel transport methods.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Reviewed-by: Mike Miller <michael.miller@canonical.com>
Reviewed-by: Joe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 3b70e66..3e501df 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -7330,6 +7330,13 @@
* 10 = 6 s/g entry or 24k
*/
+ /* If the controller supports either ioaccel method then
+ * we can also use the RAID stack submit path that does not
+ * perform the superfluous readl() after each command submission.
+ */
+ if (trans_support & (CFGTBL_Trans_io_accel1 | CFGTBL_Trans_io_accel2))
+ access = SA5_performant_access_no_read;
+
/* Controller spec: zero out this buffer. */
for (i = 0; i < h->nreply_queues; i++)
memset(h->reply_queue[i].head, 0, h->reply_queue_size);