Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752329AbcKRBNq (ORCPT ); Thu, 17 Nov 2016 20:13:46 -0500 Received: from mail.kmu-office.ch ([178.209.48.109]:40868 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750794AbcKRBNl (ORCPT ); Thu, 17 Nov 2016 20:13:41 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Date: Thu, 17 Nov 2016 17:07:24 -0800 From: Stefan Agner To: Sanchayan Maity Cc: broonie@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH 3/4] spi: spi-fsl-dspi: Fix continuous selection format In-Reply-To: References: Message-ID: User-Agent: Roundcube Webmail/1.1.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1640 Lines: 55 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... -- Stefan > dspi->tx += tx_word + 1; > > dma->tx_desc = dmaengine_prep_slave_single(dma->chan_tx,