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authorTejun Heo <htejun@gmail.com>2007-09-23 13:14:12 +0900
committerJeff Garzik <jeff@garzik.org>2007-10-12 14:55:41 -0400
commit31cc23b34913bc173680bdc87af79e551bf8cc0d (patch)
treeec64421ead9259174f0de8b22c36449ece6d69a4 /drivers/ata/libata-scsi.c
parentfb7fd61454c8681cd2621051a710b78a00369203 (diff)
libata-pmp-prep: implement ops->qc_defer()
Controllers which support PMP have various restrictions on which combinations of commands are allowed to what number of devices concurrently. This patch implements ops->qc_defer() which determines whether a qc can be issued at the moment or should be deferred. If the function returns ATA_DEFER_LINK, the qc will be deferred until a qc completes on the link. If ATA_DEFER_PORT, until a qc completes on any link. The defer conditions are advisory and in general ATA_DEFER_LINK can be considered as lower priority deferring than ATA_DEFER_PORT. ops->qc_defer() replaces fixed ata_scmd_need_defer(). For standard NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented. ahci and sata_sil24 are converted to use ata_std_qc_defer(). ops->qc_defer() is heavier than the original mechanism because full qc is prepped before determining to defer it, but various information is needed to determine defer conditinos and fully translating a qc is the only way to supply such information in generic manner. IMHO, this shouldn't cause any noticeable performance issues as * for most cases deferring occurs rarely (except for NCQ-aware cmd-switching PMP) * translation itself isn't that expensive * once deferred the command won't be repeated until another command completes which usually is a very long time cpu-wise. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/ata/libata-scsi.c')
-rw-r--r--drivers/ata/libata-scsi.c62
1 files changed, 26 insertions, 36 deletions
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index dc274001ddd..8ca2caeed01 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -749,6 +749,13 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
{
sdev->use_10_for_rw = 1;
sdev->use_10_for_ms = 1;
+
+ /* Schedule policy is determined by ->qc_defer() callback and
+ * it needs to see every deferred qc. Set dev_blocked to 1 to
+ * prevent SCSI midlayer from automatically deferring
+ * requests.
+ */
+ sdev->max_device_blocked = 1;
}
static void ata_scsi_dev_config(struct scsi_device *sdev,
@@ -1416,37 +1423,6 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
}
/**
- * ata_scmd_need_defer - Check whether we need to defer scmd
- * @dev: ATA device to which the command is addressed
- * @is_io: Is the command IO (and thus possibly NCQ)?
- *
- * NCQ and non-NCQ commands cannot run together. As upper layer
- * only knows the queue depth, we are responsible for maintaining
- * exclusion. This function checks whether a new command can be
- * issued to @dev.
- *
- * LOCKING:
- * spin_lock_irqsave(host lock)
- *
- * RETURNS:
- * 1 if deferring is needed, 0 otherwise.
- */
-static int ata_scmd_need_defer(struct ata_device *dev, int is_io)
-{
- struct ata_link *link = dev->link;
- int is_ncq = is_io && ata_ncq_enabled(dev);
-
- if (is_ncq) {
- if (!ata_tag_valid(link->active_tag))
- return 0;
- } else {
- if (!ata_tag_valid(link->active_tag) && !link->sactive)
- return 0;
- }
- return 1;
-}
-
-/**
* ata_scsi_translate - Translate then issue SCSI command to ATA device
* @dev: ATA device to which the command is addressed
* @cmd: SCSI command to execute
@@ -1477,14 +1453,12 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
void (*done)(struct scsi_cmnd *),
ata_xlat_func_t xlat_func)
{
+ struct ata_port *ap = dev->link->ap;
struct ata_queued_cmd *qc;
- int is_io = xlat_func == ata_scsi_rw_xlat;
+ int rc;
VPRINTK("ENTER\n");
- if (unlikely(ata_scmd_need_defer(dev, is_io)))
- goto defer;
-
qc = ata_scsi_qc_new(dev, cmd, done);
if (!qc)
goto err_mem;
@@ -1508,6 +1482,11 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
if (xlat_func(qc))
goto early_finish;
+ if (ap->ops->qc_defer) {
+ if ((rc = ap->ops->qc_defer(qc)))
+ goto defer;
+ }
+
/* select device, send command to hardware */
ata_qc_issue(qc);
@@ -1529,8 +1508,12 @@ err_mem:
return 0;
defer:
+ ata_qc_free(qc);
DPRINTK("EXIT - defer\n");
- return SCSI_MLQUEUE_DEVICE_BUSY;
+ if (rc == ATA_DEFER_LINK)
+ return SCSI_MLQUEUE_DEVICE_BUSY;
+ else
+ return SCSI_MLQUEUE_HOST_BUSY;
}
/**
@@ -3034,6 +3017,13 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
shost->max_channel = 1;
shost->max_cmd_len = 16;
+ /* Schedule policy is determined by ->qc_defer()
+ * callback and it needs to see every deferred qc.
+ * Set host_blocked to 1 to prevent SCSI midlayer from
+ * automatically deferring requests.
+ */
+ shost->max_host_blocked = 1;
+
rc = scsi_add_host(ap->scsi_host, ap->host->dev);
if (rc)
goto err_add;