On Thursday 02 January 2014 18:49:23 Florian Meier wrote: > Add support for DMA controller of BCM2835 as used in the Raspberry Pi. > Currently it only supports cyclic DMA. Looks very nice. Just a few details I noticed: > +#if defined(CONFIG_OF) > +static const struct of_device_id bcm2835_dma_of_match[] = { > + { .compatible = "brcm,bcm2835-dma", }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, bcm2835_dma_of_match); > +#endif I doubt we are going to see non-DT versions of this driver, so the #ifdef can just get removed here. > +static struct dma_chan *bcm2835_dma_xlate(struct of_phandle_args *spec, > + struct of_dma *ofdma) > +{ > + struct bcm2835_dmadev *d = ofdma->of_dma_data; > + struct dma_chan *chan, *candidate; > + > +retry: > + candidate = NULL; > + > + /* > + * Walk the list of channels registered with the current instance and > + * find one that is currently unused. > + */ > + list_for_each_entry(chan, &d->ddev.channels, device_node) > + if (chan->client_count == 0) { > + candidate = chan; > + break; > + } > + > + if (!candidate) > + return NULL; > + > + /* > + * dma_get_slave_channel will return NULL if we lost a race between > + * the lookup and the reservation. > + */ > + chan = dma_get_slave_channel(candidate); > + > + if (!chan) > + goto retry; > + > + /* Set DREQ from param */ > + to_bcm2835_dma_chan(chan)->dreq = spec->args[0]; > + > + return chan; > +} This can now be simplified using the dma_get_any_slave_channel() interface taht Stephen Warren introduced. > + > + if (!pdev->dev.dma_mask) > + pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask; > + > + rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32)); > + if (rc) > + return rc; > + dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32)); dma_set_mask_and_coherent() > + if (pdev->dev.of_node) { > + /* Device-tree DMA controller registration */ > + rc = of_dma_controller_register(pdev->dev.of_node, > + bcm2835_dma_xlate, od); > + if (rc) { > + dev_err(&pdev->dev, "Failed to register DMA controller\n"); > + goto err_no_dma; > + } > + } If pdev->dev.of_node isn't set, you didn't get here, so the if() can be removed. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html