On 2016-11-20 21:54, Sanchayan Maity wrote:
> Currently dmaengine_prep_slave_single was being called with length
> set to the complete DMA buffer size. This resulted in unwanted bytes
> being transferred to the SPI register leading to clock and MOSI lines
> having unwanted data even after chip select got deasserted and the
> required bytes having been transferred.
>
> While at it also clean up the use of curr_xfer_len which is central
> to the DMA setup, from bytes to DMA transfers for every use.
>
> Signed-off-by: Sanchayan Maity <maitysancha...@gmail.com>
Looks good to me:
Reviewed-by: Stefan Agner <ste...@agner.ch>
> ---
> drivers/spi/spi-fsl-dspi.c | 35 ++++++++++++++++++-----------------
> 1 file changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> index 41422cd..08882f7 100644
> --- a/drivers/spi/spi-fsl-dspi.c
> +++ b/drivers/spi/spi-fsl-dspi.c
> @@ -151,6 +151,7 @@ static const struct fsl_dspi_devtype_data ls2085a_data = {
> };
>
> struct fsl_dspi_dma {
> + /* Length of transfer in words of DSPI_FIFO_SIZE */
> u32 curr_xfer_len;
>
> u32 *tx_dma_buf;
> @@ -217,15 +218,13 @@ static void dspi_rx_dma_callback(void *arg)
> struct fsl_dspi *dspi = arg;
> struct fsl_dspi_dma *dma = dspi->dma;
> int rx_word;
> - int i, len;
> + int i;
> u16 d;
>
> rx_word = is_double_byte_mode(dspi);
>
> - len = rx_word ? (dma->curr_xfer_len / 2) : dma->curr_xfer_len;
> -
> if (!(dspi->dataflags & TRAN_STATE_RX_VOID)) {
> - for (i = 0; i < len; i++) {
> + for (i = 0; i < dma->curr_xfer_len; i++) {
> d = dspi->dma->rx_dma_buf[i];
> rx_word ? (*(u16 *)dspi->rx = d) :
> (*(u8 *)dspi->rx = d);
> @@ -242,14 +241,12 @@ static int dspi_next_xfer_dma_submit(struct
> fsl_dspi *dspi)
> struct device *dev = &dspi->pdev->dev;
> int time_left;
> int tx_word;
> - int i, len;
> + int i;
> u16 val;
>
> tx_word = is_double_byte_mode(dspi);
>
> - len = tx_word ? (dma->curr_xfer_len / 2) : dma->curr_xfer_len;
> -
> - for (i = 0; i < len - 1; i++) {
> + for (i = 0; i < dma->curr_xfer_len - 1; i++) {
> val = tx_word ? *(u16 *) dspi->tx : *(u8 *) dspi->tx;
> dspi->dma->tx_dma_buf[i] =
> SPI_PUSHR_TXDATA(val) | SPI_PUSHR_PCS(dspi->cs) |
> @@ -267,7 +264,9 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi
> *dspi)
>
> dma->tx_desc = dmaengine_prep_slave_single(dma->chan_tx,
> dma->tx_dma_phys,
> - DSPI_DMA_BUFSIZE, DMA_MEM_TO_DEV,
> + dma->curr_xfer_len *
> + DMA_SLAVE_BUSWIDTH_4_BYTES,
> + DMA_MEM_TO_DEV,
> DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> if (!dma->tx_desc) {
> dev_err(dev, "Not able to get desc for DMA xfer\n");
> @@ -283,7 +282,9 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi
> *dspi)
>
> dma->rx_desc = dmaengine_prep_slave_single(dma->chan_rx,
> dma->rx_dma_phys,
> - DSPI_DMA_BUFSIZE, DMA_DEV_TO_MEM,
> + dma->curr_xfer_len *
> + DMA_SLAVE_BUSWIDTH_4_BYTES,
> + DMA_DEV_TO_MEM,
> DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> if (!dma->rx_desc) {
> dev_err(dev, "Not able to get desc for DMA xfer\n");
> @@ -330,17 +331,17 @@ static int dspi_dma_xfer(struct fsl_dspi *dspi)
> struct device *dev = &dspi->pdev->dev;
> int curr_remaining_bytes;
> int bytes_per_buffer;
> - int tx_word;
> + int word = 1;
> int ret = 0;
>
> - tx_word = is_double_byte_mode(dspi);
> + if (is_double_byte_mode(dspi))
> + word = 2;
> curr_remaining_bytes = dspi->len;
> + bytes_per_buffer = DSPI_DMA_BUFSIZE / DSPI_FIFO_SIZE;
> while (curr_remaining_bytes) {
> /* Check if current transfer fits the DMA buffer */
> - dma->curr_xfer_len = curr_remaining_bytes;
> - bytes_per_buffer = DSPI_DMA_BUFSIZE /
> - (DSPI_FIFO_SIZE / (tx_word ? 2 : 1));
> - if (curr_remaining_bytes > bytes_per_buffer)
> + dma->curr_xfer_len = curr_remaining_bytes / word;
> + if (dma->curr_xfer_len > bytes_per_buffer)
> dma->curr_xfer_len = bytes_per_buffer;
>
> ret = dspi_next_xfer_dma_submit(dspi);
> @@ -349,7 +350,7 @@ static int dspi_dma_xfer(struct fsl_dspi *dspi)
> goto exit;
>
> } else {
> - curr_remaining_bytes -= dma->curr_xfer_len;
> + curr_remaining_bytes -= dma->curr_xfer_len * word;
> if (curr_remaining_bytes < 0)
> curr_remaining_bytes = 0;
> dspi->len = curr_remaining_bytes;
