| Message ID | 20161118080403.GB1572@Sanchayan-Arch.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2016-11-18 00:04, maitysanchayan@gmail.com wrote: > On 16-11-17 17:03:19, Stefan Agner wrote: >> 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... > > Will the below be acceptable fix? > > diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c > index 41422cd..db7f091 100644 > --- a/drivers/spi/spi-fsl-dspi.c > +++ b/drivers/spi/spi-fsl-dspi.c > @@ -217,15 +217,13 @@ 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 +240,12 @@ static int /(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 +263,9 @@ 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 +281,9 @@ 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 +330,17 @@ 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 tx_word = 1; > int ret = 0; > > - tx_word = is_double_byte_mode(dspi); > + if (is_double_byte_mode(dspi)) > + tx_word = 2; I would try to be consistent with tx_word. In most other cases it is used as boolean, whether this is a 2 byte word or not. Here you change it to represent the length of a single transfer/frame. Nothing wrong with that, just if you do such changes, also change the name of the variable so the reader does not get miss lead from other uses of "tx_word"... But otherwise looks good, like this variant much better! Maybe we should add a comment in struct fsl_dspi_dma: /* Length of transfer in words of DSPI_FIFO_SIZE */ -- Stefan > 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 / tx_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 +349,7 @@ 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 * tx_word; > if (curr_remaining_bytes < 0) > curr_remaining_bytes = 0; > dspi->len = curr_remaining_bytes; > > > Regards, > Sanchayan. >> >> -- >> 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"); -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c index 41422cd..db7f091 100644 --- a/drivers/spi/spi-fsl-dspi.c +++ b/drivers/spi/spi-fsl-dspi.c @@ -217,15 +217,13 @@ 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 +240,12 @@ 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 +263,9 @@ 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 +281,9 @@ 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 +330,17 @@ 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 tx_word = 1; int ret = 0; - tx_word = is_double_byte_mode(dspi); + if (is_double_byte_mode(dspi)) + tx_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 / tx_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 +349,7 @@ 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 * tx_word; if (curr_remaining_bytes < 0) curr_remaining_bytes = 0; dspi->len = curr_remaining_bytes;