On 2016-11-17 04:16, 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.
>
> Signed-off-by: Sanchayan Maity <maitysancha...@gmail.com>
> ---
> drivers/spi/spi-fsl-dspi.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
> index b1ee1f5..aee8c88 100644
> --- a/drivers/spi/spi-fsl-dspi.c
> +++ b/drivers/spi/spi-fsl-dspi.c
> @@ -265,7 +265,10 @@ 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 /
> + (tx_word ? 2 : 1),
> + DMA_MEM_TO_DEV,
Hm, this is getting ridiculous, I think we convert curr_xfer_len from
bytes to DMA transfers in almost every use.
Can we make it be transfer length in actual 4 byte transfers? We then
probably have to convert it to bytes once to subtract from
curr_remaining_bytes, but I think it would simplify code overall...
--
Stefan
> DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> if (!dma->tx_desc) {
> dev_err(dev, "Not able to get desc for DMA xfer\n");
> @@ -281,7 +284,10 @@ 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 /
> + (tx_word ? 2 : 1),
> + 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");
