[SCSI] aacraid: Changeable queue depth

Inspired by Brian King's patch to the ibmvscsi driver. Adds support for
a changeable queue depth to the aacraid driver.

Signed-off-by: Mark Salyzyn <aacraid@adaptec.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/scsi/aacraid/linit.c b/drivers/scsi/aacraid/linit.c
index a270a3f00647..6f92d077679f 100644
--- a/drivers/scsi/aacraid/linit.c
+++ b/drivers/scsi/aacraid/linit.c
@@ -446,6 +446,43 @@ static int aac_slave_configure(struct scsi_device *sdev)
         return 0;
 }
 
+/**
+ *      aac_change_queue_depth          -       alter queue depths
+ *      @sdev:  SCSI device we are considering
+ *      @depth: desired queue depth
+ *
+ *      Alters queue depths for target device based on the host adapter's
+ *      total capacity and the queue depth supported by the target device.
+ */
+
+static int aac_change_queue_depth(struct scsi_device *sdev, int depth)
+{
+        if (sdev->tagged_supported && (sdev->type == TYPE_DISK) &&
+            (sdev_channel(sdev) == CONTAINER_CHANNEL)) {
+                struct scsi_device * dev;
+                struct Scsi_Host *host = sdev->host;
+                unsigned num = 0;
+
+                __shost_for_each_device(dev, host) {
+                        if (dev->tagged_supported && (dev->type == TYPE_DISK) &&
+                            (sdev_channel(dev) == CONTAINER_CHANNEL))
+                                ++num;
+                        ++num;
+                }
+                if (num >= host->can_queue)
+                        num = host->can_queue - 1;
+                if (depth > (host->can_queue - num))
+                        depth = host->can_queue - num;
+                if (depth > 256)
+                        depth = 256;
+                else if (depth < 2)
+                        depth = 2;
+                scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
+        } else
+                scsi_adjust_queue_depth(sdev, 0, 1);
+        return sdev->queue_depth;
+}
+
 static int aac_ioctl(struct scsi_device *sdev, int cmd, void __user * arg)
 {
         struct aac_dev *dev = (struct aac_dev *)sdev->host->hostdata;
@@ -844,6 +881,7 @@ static struct scsi_host_template aac_driver_template = {
         .bios_param                     = aac_biosparm, 
         .shost_attrs                    = aac_attrs,
         .slave_configure                = aac_slave_configure,
+        .change_queue_depth             = aac_change_queue_depth,
         .eh_abort_handler               = aac_eh_abort,
         .eh_host_reset_handler          = aac_eh_reset,
         .can_queue                      = AAC_NUM_IO_FIB,