spi/s3c64xx: Prevent unnecessary map-unmap

Since we use DMA mode only for xfers bigger than FIFO size,
do not map/unmap buffers for polling mode transfers.
Signed-off-by: NJassi Brar <jassi.brar@samsung.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/spi/spi_s3c64xx.c

@@ -499,6 +499,7 @@ static 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;
 
@@ -514,6 +515,9 @@ 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,
@@ -545,6 +549,7 @@ 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;
 
@@ -553,6 +558,9 @@ 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,