[PATCH 2/6] SPI: S3C64XX: Prevent unnecessary map-unmap

[Jassi Brar <jassi.brar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>]

Since we use DMA mode only for xfers bigger than FIFO size,
do not map/unmap buffers for polling mode transfers.

Signed-off-by: Jassi Brar <jassi.brar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
---
 drivers/spi/spi_s3c64xx.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/spi/spi_s3c64xx.c b/drivers/spi/spi_s3c64xx.c
index 774e861..12e7915 100644
--- a/drivers/spi/spi_s3c64xx.c
+++ b/drivers/spi/spi_s3c64xx.c
@@ -492,6 +492,7 @@ void s3c64xx_spi_dma_txcb(struct s3c2410_dma_chan *chan, void *buf_id,
 static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
 						struct spi_message *msg)
 {
+	struct s3c64xx_spi_info *sci = sdd->cntrlr_info;
 	struct device *dev = &sdd->pdev->dev;
 	struct spi_transfer *xfer;
 
@@ -507,6 +508,9 @@ static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
 	/* Map until end or first fail */
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 
+		if (xfer->len <= ((sci->fifo_lvl_mask >> 1) + 1))
+			continue;
+
 		if (xfer->tx_buf != NULL) {
 			xfer->tx_dma = dma_map_single(dev,
 					(void *)xfer->tx_buf, xfer->len,
@@ -538,6 +542,7 @@ static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
 static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
 						struct spi_message *msg)
 {
+	struct s3c64xx_spi_info *sci = sdd->cntrlr_info;
 	struct device *dev = &sdd->pdev->dev;
 	struct spi_transfer *xfer;
 
@@ -546,6 +551,9 @@ static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 
+		if (xfer->len <= ((sci->fifo_lvl_mask >> 1) + 1))
+			continue;
+
 		if (xfer->rx_buf != NULL
 				&& xfer->rx_dma != XFER_DMAADDR_INVALID)
 			dma_unmap_single(dev, xfer->rx_dma,
-- 
1.6.2.5


------------------------------------------------------------------------------
This SF.net Dev2Dev email is sponsored by:

Show off your parallel programming skills.
Enter the Intel(R) Threading Challenge 2010.
http://p.sf.net/sfu/intel-thread-sfd