libata-pmp-prep: implement ops->qc_defer()

[safe/jmp/linux-2.6] / drivers / ata / libata-core.c

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 9467c2f..b666f51 100644 (file)
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4346,6 +4346,36 @@ int ata_check_atapi_dma(struct ata_queued_cmd *qc)
 }
 
 /**
+ *     ata_std_qc_defer - Check whether a qc needs to be deferred
+ *     @qc: ATA command in question
+ *
+ *     Non-NCQ commands cannot run with any other command, NCQ or
+ *     not.  As upper layer only knows the queue depth, we are
+ *     responsible for maintaining exclusion.  This function checks
+ *     whether a new command @qc can be issued.
+ *
+ *     LOCKING:
+ *     spin_lock_irqsave(host lock)
+ *
+ *     RETURNS:
+ *     ATA_DEFER_* if deferring is needed, 0 otherwise.
+ */
+int ata_std_qc_defer(struct ata_queued_cmd *qc)
+{
+       struct ata_link *link = qc->dev->link;
+
+       if (qc->tf.protocol == ATA_PROT_NCQ) {
+               if (!ata_tag_valid(link->active_tag))
+                       return 0;
+       } else {
+               if (!ata_tag_valid(link->active_tag) && !link->sactive)
+                       return 0;
+       }
+
+       return ATA_DEFER_LINK;
+}
+
+/**
  *     ata_qc_prep - Prepare taskfile for submission
  *     @qc: Metadata associated with taskfile to be prepared
  *
@@ -7111,6 +7141,7 @@ EXPORT_SYMBOL_GPL(ata_interrupt);
 EXPORT_SYMBOL_GPL(ata_do_set_mode);
 EXPORT_SYMBOL_GPL(ata_data_xfer);
 EXPORT_SYMBOL_GPL(ata_data_xfer_noirq);
+EXPORT_SYMBOL_GPL(ata_std_qc_defer);
 EXPORT_SYMBOL_GPL(ata_qc_prep);
 EXPORT_SYMBOL_GPL(ata_dumb_qc_prep);
 EXPORT_SYMBOL_GPL(ata_noop_qc_prep);