[PATCH 10/11] ahci: add PIOS interim interrupt handling

[Tejun Heo <htejun@gmail.com>]

During multiblock PIO, multiple PIOS interrupts are generated before
qc compltion.  Current code prints unnecessary message for such cases.
This is exposed when new EH slows down attached device into PIO mode.

Signed-off-by: Tejun Heo <htejun@gmail.com>

---

 drivers/scsi/ahci.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

ad7facff3665ce6527929ec5b9c6b2a04689010c
diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index c2b9c93..680dd5b 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -899,7 +899,18 @@ static void ahci_host_intr(struct ata_po
 		}
 	}
 
-	/* spurious interrupt */
+	/* hmmm... a spurious interupt */
+
+	/* ignore interim PIO setup fis interrupts */
+	if (ata_tag_valid(ap->active_tag)) {
+		struct ata_queued_cmd *qc =
+			ata_qc_from_tag(ap, ap->active_tag);
+
+		if (qc && qc->tf.protocol == ATA_PROT_PIO &&
+		    (status & PORT_IRQ_PIOS_FIS))
+			return;
+	}
+
 	if (ata_ratelimit())
 		ata_port_printk(ap, KERN_INFO, "spurious interrupt "
 				"(irq_stat 0x%x active_tag %d)\n",
-- 
1.2.4