From 159a7ff7a13f9a02c75006f40c0561a3a81aefcd Mon Sep 17 00:00:00 2001
From: Gwendal Grignou <gwendal@google.com>
Date: Mon, 12 Oct 2009 15:44:00 -0700
Subject: [PATCH] sata_mv: Prevent PIO commands to be defered too long if
traffic in progress.
Use excl_link when non NCQ commands are defered, to be sure they are processed
as soon as outstanding commands are completed. It prevents some commands to be
defered indifinitely when using a port multiplier.
Signed-off-by: Gwendal Grignou <gwendal@google.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
---
drivers/ata/sata_mv.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 17f9ff9067a2..6f5093b7c8c5 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -1382,6 +1382,25 @@ static int mv_qc_defer(struct ata_queued_cmd *qc)
*/
if (pp->pp_flags & MV_PP_FLAG_DELAYED_EH)
return ATA_DEFER_PORT;
+
+ /* PIO commands need exclusive link: no other commands [DMA or PIO]
+ * can run concurrently.
+ * set excl_link when we want to send a PIO command in DMA mode
+ * or a non-NCQ command in NCQ mode.
+ * When we receive a command from that link, and there are no
+ * outstanding commands, mark a flag to clear excl_link and let
+ * the command go through.
+ */
+ if (unlikely(ap->excl_link)) {
+ if (link == ap->excl_link) {
+ if (ap->nr_active_links)
+ return ATA_DEFER_PORT;
+ qc->flags |= ATA_QCFLAG_CLEAR_EXCL;
+ return 0;
+ } else
+ return ATA_DEFER_PORT;
+ }
+
/*
* If the port is completely idle, then allow the new qc.
*/
@@ -1395,8 +1414,14 @@ static int mv_qc_defer(struct ata_queued_cmd *qc)
* doesn't allow it.
*/
if ((pp->pp_flags & MV_PP_FLAG_EDMA_EN) &&
- (pp->pp_flags & MV_PP_FLAG_NCQ_EN) && ata_is_ncq(qc->tf.protocol))
- return 0;
+ (pp->pp_flags & MV_PP_FLAG_NCQ_EN)) {
+ if (ata_is_ncq(qc->tf.protocol))
+ return 0;
+ else {
+ ap->excl_link = link;
+ return ATA_DEFER_PORT;
+ }
+ }
return ATA_DEFER_PORT;
}
--
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