From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@bootlin.com (Maxime Ripard) Date: Tue, 3 Apr 2018 10:17:11 +0200 Subject: [PATCH 6/6] spi: sun4i: add DMA transfers support In-Reply-To: <20180329185907.27281-7-ssuloev@orpaltech.com> References: <20180329185907.27281-1-ssuloev@orpaltech.com> <20180329185907.27281-7-ssuloev@orpaltech.com> Message-ID: <20180403081711.rqsp77mgnuvlnzt5@flea> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Mar 29, 2018 at 09:59:07PM +0300, Sergey Suloev wrote: > +static int sun4i_spi_dma_setup(struct device *dev, > + struct resource *res) > +{ > + struct spi_master *master = dev_get_drvdata(dev); > + struct dma_slave_config dma_sconf; > + int ret; > + > + master->dma_tx = dma_request_slave_channel_reason(dev, "tx"); > + if (IS_ERR(master->dma_tx)) { > + dev_err(dev, "Unable to acquire DMA TX channel\n"); > + ret = PTR_ERR(master->dma_tx); > + goto out; > + } > + > + dma_sconf.direction = DMA_MEM_TO_DEV; > + dma_sconf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > + dma_sconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; I guess that would depend on the size of the transfer, right? > + dma_sconf.dst_addr = res->start + SUN4I_TXDATA_REG; > + dma_sconf.dst_maxburst = 1; > + dma_sconf.src_maxburst = 1; And a burst of 1 seems sub-optimal here. > + ret = sun4i_spi_dma_setup(&pdev->dev, res); > + if (ret) { > + if (ret == -EPROBE_DEFER) { > + /* wait for the dma driver to load */ > + goto err_free_master; > + } > + dev_warn(&pdev->dev, "DMA transfer not supported\n"); Saying why it's not supported would be great. Maxime -- Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: