1 files changed, 21 insertions, 31 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index a5f03dd8d8da..f5129390bc2d 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -38,8 +38,6 @@
 
 #define CS_DEFAULT      0xFF
 
-#define SPI_BUFSIZ      (SMP_CACHE_BYTES + 1)
-
 #define SPIFMT_PHASE_MASK       BIT(16)
 #define SPIFMT_POLARITY_MASK    BIT(17)
 #define SPIFMT_DISTIMER_MASK    BIT(18)
@@ -140,7 +138,6 @@ struct davinci_spi {
 
         const void              *tx;
         void                    *rx;
-        u8                      *tmp_buf;
         int                     rcount;
         int                     wcount;
         struct davinci_spi_dma  dma_channels;
@@ -718,7 +715,7 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
 {
         struct davinci_spi *davinci_spi;
         int int_status = 0;
-        int count, temp_count;
+        int count;
         struct davinci_spi_dma *davinci_spi_dma;
         int data_type, ret;
         unsigned long tx_reg, rx_reg;
@@ -750,6 +747,18 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
         /* Enable SPI */
         set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
 
+        /*
+         * Transmit DMA setup
+         *
+         * If there is transmit data, map the transmit buffer, set it as the
+         * source of data and set the source B index to data size.
+         * If there is no transmit data, set the transmit register as the
+         * source of data, and set the source B index to zero.
+         *
+         * The destination is always the transmit register itself. And the
+         * destination never increments.
+         */
+
         if (t->tx_buf) {
                 t->tx_dma = dma_map_single(&spi->dev, (void *)t->tx_buf, count,
                                 DMA_TO_DEVICE);
@@ -758,25 +767,15 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
                                 " TX buffer\n", count);
                         return -ENOMEM;
                 }
-                temp_count = count;
-        } else {
-                /* We need TX clocking for RX transaction */
-                t->tx_dma = dma_map_single(&spi->dev,
-                                (void *)davinci_spi->tmp_buf, count + 1,
-                                DMA_TO_DEVICE);
-                if (dma_mapping_error(&spi->dev, t->tx_dma)) {
-                        dev_dbg(sdev, "Unable to DMA map a %d bytes"
-                                " TX tmp buffer\n", count);
-                        return -ENOMEM;
-                }
-                temp_count = count + 1;
         }
 
         edma_set_transfer_params(davinci_spi_dma->dma_tx_channel,
-                                        data_type, temp_count, 1, 0, ASYNC);
+                                        data_type, count, 1, 0, ASYNC);
         edma_set_dest(davinci_spi_dma->dma_tx_channel, tx_reg, INCR, W8BIT);
-        edma_set_src(davinci_spi_dma->dma_tx_channel, t->tx_dma, INCR, W8BIT);
-        edma_set_src_index(davinci_spi_dma->dma_tx_channel, data_type, 0);
+        edma_set_src(davinci_spi_dma->dma_tx_channel,
+                        t->tx_buf ? t->tx_dma : tx_reg, INCR, W8BIT);
+        edma_set_src_index(davinci_spi_dma->dma_tx_channel,
+                        t->tx_buf ? data_type : 0, 0);
         edma_set_dest_index(davinci_spi_dma->dma_tx_channel, 0, 0);
 
         if (t->rx_buf) {
@@ -818,7 +817,8 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
                 wait_for_completion_interruptible(
                                 &davinci_spi_dma->dma_rx_completion);
 
-        dma_unmap_single(NULL, t->tx_dma, temp_count, DMA_TO_DEVICE);
+        if (t->tx_buf)
+                dma_unmap_single(NULL, t->tx_dma, count, DMA_TO_DEVICE);
 
         if (t->rx_buf)
                 dma_unmap_single(NULL, t->rx_dma, count, DMA_FROM_DEVICE);
@@ -906,17 +906,10 @@ static int davinci_spi_probe(struct platform_device *pdev)
         if (ret)
                 goto unmap_io;
 
-        /* Allocate tmp_buf for tx_buf */
-        davinci_spi->tmp_buf = kzalloc(SPI_BUFSIZ, GFP_KERNEL);
-        if (davinci_spi->tmp_buf == NULL) {
-                ret = -ENOMEM;
-                goto irq_free;
-        }
-
         davinci_spi->bitbang.master = spi_master_get(master);
         if (davinci_spi->bitbang.master == NULL) {
                 ret = -ENODEV;
-                goto free_tmp_buf;
+                goto irq_free;
         }
 
         davinci_spi->clk = clk_get(&pdev->dev, NULL);
@@ -1027,8 +1020,6 @@ free_clk:
         clk_put(davinci_spi->clk);
 put_master:
         spi_master_put(master);
-free_tmp_buf:
-        kfree(davinci_spi->tmp_buf);
 irq_free:
         free_irq(davinci_spi->irq, davinci_spi);
 unmap_io:
@@ -1063,7 +1054,6 @@ static int __exit davinci_spi_remove(struct platform_device *pdev)
         clk_disable(davinci_spi->clk);
         clk_put(davinci_spi->clk);
         spi_master_put(master);
-        kfree(davinci_spi->tmp_buf);
         free_irq(davinci_spi->irq, davinci_spi);
         iounmap(davinci_spi->base);
         release_mem_region(davinci_spi->pbase, davinci_spi->region_size);