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
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