From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Agner Subject: Re: [PATCH v2 3/4] spi: spi-fsl-dspi: Fix incorrect DMA setup Date: Mon, 21 Nov 2016 15:16:51 -0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sanchayan Maity Return-path: In-Reply-To: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 Looks good to me: Reviewed-by: Stefan Agner > --- > 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; -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html