| Message ID | d83f4896d77f577ca92fd70534f6198bb3288d8a.1479384571.git.maitysanchayan@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 <maitysanchayan@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");
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, 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");
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 <maitysanchayan@gmail.com> --- drivers/spi/spi-fsl-dspi.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)