From 31cc23b34913bc173680bdc87af79e551bf8cc0d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 23 Sep 2007 13:14:12 +0900 Subject: 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 Signed-off-by: Jeff Garzik --- drivers/ata/libata-scsi.c | 62 ++++++++++++++++++++--------------------------- 1 file changed, 26 insertions(+), 36 deletions(-) (limited to 'drivers/ata/libata-scsi.c') 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, @@ -1415,37 +1422,6 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc) ata_qc_free(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 @@ -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; -- cgit v1.2.3-70-g09d2