Hi Paul, On Tue, Jul 03, 2018 at 02:32:02PM +0200, Paul Cercueil wrote: > @@ -804,9 +818,19 @@ static int jz4780_dma_probe(struct platform_device *pdev) > return -EINVAL; > } > > - jzdma->base = devm_ioremap_resource(dev, res); > - if (IS_ERR(jzdma->base)) > - return PTR_ERR(jzdma->base); > + jzdma->chn_base = devm_ioremap_resource(dev, res); > + if (IS_ERR(jzdma->chn_base)) > + return PTR_ERR(jzdma->chn_base); > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 1); > + if (!res) { > + dev_err(dev, "failed to get I/O memory\n"); > + return -EINVAL; > + } > + > + jzdma->ctrl_base = devm_ioremap_resource(dev, res); > + if (IS_ERR(jzdma->ctrl_base)) > + return PTR_ERR(jzdma->ctrl_base); Could we have this failure case fall back to the existing behaviour where we only have a single resource covering all the registers? That would avoid breaking bisection between this patch & the one that updates the JZ4780 DT. For example: #define JZ4780_DMA_CTRL_OFFSET 0x1000 res = platform_get_resource(pdev, IORESOURCE_MEM, 1); if (res) { jzdma->ctrl_base = devm_ioremap_resource(dev, res); if (IS_ERR(jzdma->ctrl_base)) return PTR_ERR(jzdma->ctrl_base); } else { jzdma->ctrl_base = jzdma->chn_base + JZ4780_DMA_CTRL_OFFSET; } Then you could remove the fallback after patch 13, to end up with the same code you have now but without breaking bisection. Most correct might be to move patch 13 to right after this one, so that the JZ4780-specific fallback can be removed before adding support for any of the other SoCs. Thanks, Paul -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html