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