[SCSI] megaraid: Add support for change_queue_depth

Adds support for change_queue_depth so that device
queue depth can be changed at runtime through sysfs.

Signed-off-by: <brking@charter.net>
Acked-by: Seokmann Ju <seokmann.ju@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/scsi/megaraid/megaraid_mbox.c b/drivers/scsi/megaraid/megaraid_mbox.c
index 92715130ac09..7ae580f17e64 100644
--- a/drivers/scsi/megaraid/megaraid_mbox.c
+++ b/drivers/scsi/megaraid/megaraid_mbox.c
@@ -330,6 +330,21 @@ static struct device_attribute *megaraid_sdev_attrs[] = {
         NULL,
 };
 
+/**
+ * megaraid_change_queue_depth - Change the device's queue depth
+ * @sdev:       scsi device struct
+ * @qdepth:     depth to set
+ *
+ * Return value:
+ *      actual depth set
+ **/
+static int megaraid_change_queue_depth(struct scsi_device *sdev, int qdepth)
+{
+        if (qdepth > MBOX_MAX_SCSI_CMDS)
+                qdepth = MBOX_MAX_SCSI_CMDS;
+        scsi_adjust_queue_depth(sdev, 0, qdepth);
+        return sdev->queue_depth;
+}
 
 /*
  * Scsi host template for megaraid unified driver
@@ -343,6 +358,7 @@ static struct scsi_host_template megaraid_template_g = {
         .eh_device_reset_handler        = megaraid_reset_handler,
         .eh_bus_reset_handler           = megaraid_reset_handler,
         .eh_host_reset_handler          = megaraid_reset_handler,
+        .change_queue_depth             = megaraid_change_queue_depth,
         .use_clustering                 = ENABLE_CLUSTERING,
         .sdev_attrs                     = megaraid_sdev_attrs,
         .shost_attrs                    = megaraid_shost_attrs,