spi: sirf: fix spi full-duplex DMA transferring issue

sometimes t->tx can be equal with t->rx. for example, spidev will make
tx and rx point to spidev->buffer at the same time. currently, for this
case, we map the buffer BIDIRECTION to fix the cache consistency.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/drivers/spi/spi-sirf.c b/drivers/spi/spi-sirf.c
index 3c12f396d96a3223664fae8d633f15f583ce7545..0c039d4542a5b3f6437be5f52eb9cefdf1aa2607 100644 (file)
--- a/drivers/spi/spi-sirf.c
+++ b/drivers/spi/spi-sirf.c
@@ -383,7 +383,8 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
                struct dma_async_tx_descriptor *rx_desc, *tx_desc;
 
                sspi->dst_start = dma_map_single(&spi->dev,
-                               sspi->rx, t->len, DMA_FROM_DEVICE);
+                               sspi->rx, t->len, (t->tx_buf != t->rx_buf) ?
+                               DMA_FROM_DEVICE : DMA_BIDIRECTIONAL);
                rx_desc = dmaengine_prep_slave_single(sspi->rx_chan,
                        sspi->dst_start, t->len, DMA_DEV_TO_MEM,
                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
@@ -391,7 +392,9 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
                rx_desc->callback_param = &sspi->rx_done;
 
                sspi->src_start = dma_map_single(&spi->dev,
-                               (void *)sspi->tx, t->len, DMA_TO_DEVICE);
+                               (void *)sspi->tx, t->len,
+                               (t->tx_buf != t->rx_buf) ?
+                               DMA_TO_DEVICE : DMA_BIDIRECTIONAL);
                tx_desc = dmaengine_prep_slave_single(sspi->tx_chan,
                        sspi->src_start, t->len, DMA_MEM_TO_DEV,
                        DMA_PREP_INTERRUPT | DMA_CTRL_ACK);