[PATCH v2 07/23] ata: sata_dwc_460ex: skip dma setup for non-dma commands

From: Andy Shevchenko
Date: Tue Apr 26 2016 - 05:08:59 EST


From: Mans Rullgard <mans@xxxxxxxxx>

Calling dmaengine_prep_slave_sg() for non-dma ATA commands is
unnecessary at best and could be harmful if the dma driver reacts
badly to this. It also causes this driver to print a bogus error
message in these cases.

This patch changes sata_dwc_qc_issue() to only do the dma setup
for dma commands and also reports an error to libata if if fails.

Tested-by: Christian Lamparter <chunkeey@xxxxxxxxxxxxxx>
Signed-off-by: Mans Rullgard <mans@xxxxxxxxx>
---
drivers/ata/sata_dwc_460ex.c | 35 +++++++++--------------------------
1 file changed, 9 insertions(+), 26 deletions(-)

diff --git a/drivers/ata/sata_dwc_460ex.c b/drivers/ata/sata_dwc_460ex.c
index 1250e18..038e5fb 100644
--- a/drivers/ata/sata_dwc_460ex.c
+++ b/drivers/ata/sata_dwc_460ex.c
@@ -1023,36 +1023,12 @@ static void sata_dwc_bmdma_start(struct ata_queued_cmd *qc)
sata_dwc_bmdma_start_by_tag(qc, tag);
}

-/*
- * Function : sata_dwc_qc_prep_by_tag
- * arguments : ata_queued_cmd *qc, u8 tag
- * Return value : None
- * qc_prep for a particular queued command based on tag
- */
-static void sata_dwc_qc_prep_by_tag(struct ata_queued_cmd *qc, u8 tag)
-{
- struct dma_async_tx_descriptor *desc;
- struct ata_port *ap = qc->ap;
- struct sata_dwc_device_port *hsdevp = HSDEVP_FROM_AP(ap);
-
- dev_dbg(ap->dev, "%s: port=%d dma dir=%s n_elem=%d\n",
- __func__, ap->port_no, get_dma_dir_descript(qc->dma_dir),
- qc->n_elem);
-
- desc = dma_dwc_xfer_setup(qc);
- if (!desc) {
- dev_err(ap->dev, "%s: dma_dwc_xfer_setup returns NULL\n",
- __func__);
- return;
- }
- hsdevp->desc[tag] = desc;
-}
-
static unsigned int sata_dwc_qc_issue(struct ata_queued_cmd *qc)
{
u32 sactive;
u8 tag = qc->tag;
struct ata_port *ap = qc->ap;
+ struct sata_dwc_device_port *hsdevp = HSDEVP_FROM_AP(ap);

#ifdef DEBUG_NCQ
if (qc->tag > 0 || ap->link.sactive > 1)
@@ -1066,7 +1042,14 @@ static unsigned int sata_dwc_qc_issue(struct ata_queued_cmd *qc)

if (!ata_is_ncq(qc->tf.protocol))
tag = 0;
- sata_dwc_qc_prep_by_tag(qc, tag);
+
+ if (ata_is_dma(qc->tf.protocol)) {
+ hsdevp->desc[tag] = dma_dwc_xfer_setup(qc);
+ if (!hsdevp->desc[tag])
+ return AC_ERR_SYSTEM;
+ } else {
+ hsdevp->desc[tag] = NULL;
+ }

if (ata_is_ncq(qc->tf.protocol)) {
sactive = core_scr_read(SCR_ACTIVE);
--
2.8.0.rc3