Grant Grundler wrote:
On Wed, May 20, 2009 at 12:00 AM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
libata currently has a pretty dumb ATA_MAX_QUEUE loop for finding
a free tag to use. Instead of fixing that up, convert libata to
using block layer tagging - gets rid of code in libata, and is also
much faster.
...
@@ -1137,7 +1141,17 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
depth = min(ATA_MAX_QUEUE - 1, depth);
- scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
+
+ /*
+ * If this device is behind a port multiplier, we have
+ * to share the tag map between all devices on that PMP.
+ * Set up the shared tag map here and we get automatic.
Automatic what?
+ */
+ if (dev->link->ap->pmp_link)
+ scsi_init_shared_tag_map(sdev->host, ATA_MAX_QUEUE - 1);
+
+ scsi_set_tag_type(sdev, MSG_SIMPLE_TAG);
+ scsi_activate_tcq(sdev, depth);
I just read Tejun's reply and it sounds right what he's saying.
But can SATA controllers handle NCQ and !NCQ devices on the same port?
Can the PMP handle it?
If both can, I don't understand how a mixed config works today.
A mixed config over PMP works today by setting the proper depth iff NCQ
(== will not send too many cmds to device, if !NCQ) and using link-wide
tag allocation (== will not send too many cmds to link).
Jeff
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