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SubjectRe: [PATCH 2/2] dmaengine: uniphier-xdmac: Add UniPhier external DMA controller driver
On 18-12-19, 09:57, Kunihiko Hayashi wrote:
> This adds external DMA controller driver implemented in Socionext
> UniPhier SoCs. This driver supports DMA_MEMCPY and DMA_SLAVE modes.
>
> Since this driver does not support the the way to transfer size
> unaligned to burst width, 'src_maxburst' or 'dst_maxburst' of

You mean driver does not support any unaligned bursts?

> +static int uniphier_xdmac_probe(struct platform_device *pdev)
> +{
> + struct uniphier_xdmac_device *xdev;
> + struct device *dev = &pdev->dev;
> + struct dma_device *ddev;
> + int irq;
> + int nr_chans;
> + int i, ret;
> +
> + if (of_property_read_u32(dev->of_node, "dma-channels", &nr_chans))
> + return -EINVAL;
> + if (nr_chans > XDMAC_MAX_CHANS)
> + nr_chans = XDMAC_MAX_CHANS;
> +
> + xdev = devm_kzalloc(dev, struct_size(xdev, channels, nr_chans),
> + GFP_KERNEL);
> + if (!xdev)
> + return -ENOMEM;
> +
> + xdev->nr_chans = nr_chans;
> + xdev->reg_base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(xdev->reg_base))
> + return PTR_ERR(xdev->reg_base);
> +
> + ddev = &xdev->ddev;
> + ddev->dev = dev;
> + dma_cap_zero(ddev->cap_mask);
> + dma_cap_set(DMA_MEMCPY, ddev->cap_mask);
> + dma_cap_set(DMA_SLAVE, ddev->cap_mask);
> + ddev->src_addr_widths = UNIPHIER_XDMAC_BUSWIDTHS;
> + ddev->dst_addr_widths = UNIPHIER_XDMAC_BUSWIDTHS;
> + ddev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
> + BIT(DMA_MEM_TO_MEM);
> + ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> + ddev->max_burst = XDMAC_MAX_WORDS;
> + ddev->device_free_chan_resources = uniphier_xdmac_free_chan_resources;
> + ddev->device_prep_dma_memcpy = uniphier_xdmac_prep_dma_memcpy;
> + ddev->device_prep_slave_sg = uniphier_xdmac_prep_slave_sg;
> + ddev->device_config = uniphier_xdmac_slave_config;
> + ddev->device_terminate_all = uniphier_xdmac_terminate_all;
> + ddev->device_synchronize = uniphier_xdmac_synchronize;
> + ddev->device_tx_status = dma_cookie_status;
> + ddev->device_issue_pending = uniphier_xdmac_issue_pending;
> + INIT_LIST_HEAD(&ddev->channels);
> +
> + for (i = 0; i < nr_chans; i++) {
> + ret = uniphier_xdmac_chan_init(xdev, i);
> + if (ret) {
> + dev_err(dev,
> + "Failed to initialize XDMAC channel %d\n", i);
> + return ret;

so on error for channel N we leave N-1 channels initialized?

> +static int uniphier_xdmac_remove(struct platform_device *pdev)
> +{
> + struct uniphier_xdmac_device *xdev = platform_get_drvdata(pdev);
> + struct dma_device *ddev = &xdev->ddev;
> + struct dma_chan *chan;
> + int ret;
> +
> + /*
> + * Before reaching here, almost all descriptors have been freed by the
> + * ->device_free_chan_resources() hook. However, each channel might
> + * be still holding one descriptor that was on-flight at that moment.
> + * Terminate it to make sure this hardware is no longer running. Then,
> + * free the channel resources once again to avoid memory leak.
> + */
> + list_for_each_entry(chan, &ddev->channels, device_node) {
> + ret = dmaengine_terminate_sync(chan);
> + if (ret)
> + return ret;
> + uniphier_xdmac_free_chan_resources(chan);

terminating sounds okayish but not freeing here. .ree_chan_resources()
should have been called already and that should ensure that termination
is already done...

--
~Vinod

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