Flush the transfer before exiting from write function.

Since the buffer is used by the DMA, if we return early we run the
risk of having the buffer overwritten before the transfer will be
completed.
Waiting for the flush could be theorically a pessimization, but from
tests, since the typical use involves mixed reads/writes, we already
wait for the transfers to be completed, and performance are
almost the same.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4017 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/bertos/cpu/arm/drv/spi_dma_at91.c b/bertos/cpu/arm/drv/spi_dma_at91.c
index 03b98d85e390f8f3d776b8759c3080f28155b016..25a104103705be0e6af8fb1a1697d5828038ae65 100644 (file)
--- a/bertos/cpu/arm/drv/spi_dma_at91.c
+++ b/bertos/cpu/arm/drv/spi_dma_at91.c
@@ -76,11 +76,11 @@ static int spi_dma_flush(UNUSED_ARG(struct KFile *, fd))
 
 static size_t spi_dma_write(struct KFile *fd, const void *_buf, size_t size)
 {
-       spi_dma_flush(fd);
        SPI0_PTCR = BV(PDC_TXTDIS);
        SPI0_TPR = (reg32_t)_buf;
        SPI0_TCR = size;
        SPI0_PTCR = BV(PDC_TXTEN);
+       spi_dma_flush(fd);
        return size;
 }
 
@@ -97,8 +97,6 @@ static size_t spi_dma_read(struct KFile *fd, void *_buf, size_t size)
        size_t count, total_rx = 0;
        uint8_t *buf = (uint8_t *)_buf;
 
-       spi_dma_flush(fd);
-
        while (size)
        {
                count = MIN(size, (size_t)CONFIG_SPI_DMA_MAX_RX);