From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH 3/3] spi:fsl-dspi:add dspi dma transfer support Date: Tue, 25 Feb 2014 09:15:08 +0000 Message-ID: <20140225091508.GP28555@e106331-lin.cambridge.arm.com> References: <1393311258-14380-1-git-send-email-b44548@freescale.com> <1393311258-14380-3-git-send-email-b44548@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" To: Chao Fu Return-path: Content-Disposition: inline In-Reply-To: <1393311258-14380-3-git-send-email-b44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: On Tue, Feb 25, 2014 at 06:54:18AM +0000, Chao Fu wrote: > From: Chao Fu > > DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA > transfer driver support. Add DMA reference functions and variables to form DMA > transfer process. > DSPI DMA mode need work with Freescale eDMA module together. > > The software will be changed in two transfer methods as followwing: > DMA PIO > trigger write: dspi_tx_dma dspi_tx_pio > write complete: dspi_dma_tx_complete irq_handle > trigger read: dspi_receive_dma dspi_rx_pio > read complete: dspi_rx_dma none > > Remove bitbang: > Add DMA funtions, DSPI module need get cs change information in a spi transfer. > According cs change, DSPI will give last data the right flag. Bitbang provide > cs change behind the last data in a transfer. DSPI can not deal the last data in > every transfer properly, so remove the bitbang in driver. > > Signed-off-by: Chao Fu > --- > drivers/spi/Kconfig | 1 - > drivers/spi/spi-fsl-dspi.c | 425 ++++++++++++++++++++++++++++++++++++++------- > 2 files changed, 360 insertions(+), 66 deletions(-) [...] > @@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev) > } > clk_prepare_enable(dspi->clk); > > + dspi->use_dma = of_property_read_bool(np, "use-dma"); > + if (dspi->use_dma) > + if (dspi_request_dma(dspi)) { > + dspi->use_dma = 0; > + dev_err(&pdev->dev, "request dma channel fail\n"); > + dspi_release_dma(dspi); > + } Why have the use-dma property at all? You already fall back to PIO mode if the DMAs are not present, so it's clearly not a requirement to use DMA. Why not always try to request he dmas you need? You already have the fallback logic, the only difference would be changing the dev_err to better describe the situation: dev_info(&pdev->dev, "No 'tx' and/or 'rx' DMA(s), using PIO mode\n"); Cheers, Mark. -- 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