Messages in this thread | | | Date | Tue, 3 Apr 2018 10:17:11 +0200 | From | Maxime Ripard <> | Subject | Re: [PATCH 6/6] spi: sun4i: add DMA transfers support |
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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 [unhandled content-type:application/pgp-signature] | |