From mboxrd@z Thu Jan 1 00:00:00 1970 From: maitysanchayan-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Subject: Re: [PATCH 3/4] spi: spi-fsl-dspi: Fix continuous selection format Date: Fri, 18 Nov 2016 13:29:27 +0530 Message-ID: <20161118075927.GA1572@Sanchayan-Arch.localdomain> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 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: Stefan Agner Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Hello Stefan, On 16-11-17 17:07:24, Stefan Agner wrote: > On 2016-11-17 04:16, Sanchayan Maity wrote: > > Current DMA implementation was not handling the continuous selection > > format viz. SPI chip select would be deasserted even between sequential > > serial transfers. Use the cs_change variable and correctly set or > > reset the CONT bit accordingly for case where peripherals require > > the chip select to be asserted between sequential transfers. > > > > Signed-off-by: Sanchayan Maity > > --- > > drivers/spi/spi-fsl-dspi.c | 13 ++++++++++--- > > 1 file changed, 10 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c > > index aee8c88..164e2e1 100644 > > --- a/drivers/spi/spi-fsl-dspi.c > > +++ b/drivers/spi/spi-fsl-dspi.c > > @@ -258,9 +258,16 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi *dspi) > > } > > > > val = tx_word ? *(u16 *) dspi->tx : *(u8 *) dspi->tx; > > - dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) | > > - SPI_PUSHR_PCS(dspi->cs) | > > - SPI_PUSHR_CTAS(0); > > + if (dspi->cs_change) { > > + dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) | > > + SPI_PUSHR_PCS(dspi->cs) | > > + SPI_PUSHR_CTAS(0); > > + } else { > > + dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) | > > + SPI_PUSHR_PCS(dspi->cs) | > > + SPI_PUSHR_CTAS(0) | > > + SPI_PUSHR_CONT; > > + } > > How about: > > > dspi->dma->tx_dma_buf[i] = SPI_PUSHR_TXDATA(val) | > SPI_PUSHR_PCS(dspi->cs) | > SPI_PUSHR_CTAS(0); > > + if (dspi->cs_change) > + dspi->dma->tx_dma_buf[i] |= SPI_PUSHR_CONT; > > > Avoids code duplication... Agreed. It's much better. Should be !dspi->cs_change though. Will include it in next iteration. Thanks & Regards, Sanchayan. > > -- > Stefan > > > > > dspi->tx += tx_word + 1; > > > > dma->tx_desc = dmaengine_prep_slave_single(dma->chan_tx, -- 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