Re: [PATCH v5 08/10] dmaengine: tegra: Use iommu-map for stream ID

Frank Li
2026-03-30T16:47:34Z

On Mon, Mar 30, 2026 at 08:14:54PM +0530, Akhil R wrote:
> Use 'iommu-map', when provided, to get the stream ID to be programmed
> for each channel. Iterate over the channels registered and configure
> each channel device separately using of_dma_configure_id() to allow
> it to use a separate IOMMU domain for the transfer. However, do this
> in a second loop since the first loop populates the DMA device channels
> list and async_device_register() registers the channels. Both are
> prerequisites for using the channel device in the next loop.
>
> Channels will continue to use the same global stream ID if the
> 'iommu-map' property is not present in the device tree.
>
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> ---
...
>
> + /*
> + * Configure stream ID for each channel from the channels registered
> + * above. This is done in a separate iteration to ensure that only
> + * the channels available and registered for the DMA device are used.
> + */
> + list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
> + chdev = &chan->dev->device;
> + tdc = to_tegra_dma_chan(chan);
> +
> + if (use_iommu_map) {
> + chdev->bus = pdev->dev.bus;
> + dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
> +
> + ret = of_dma_configure_id(chdev, pdev->dev.of_node,
> + true, &tdc->id);
> + if (ret)
> + return dev_err_probe(chdev, ret,
> + "Failed to configure IOMMU for channel %d", tdc->id);
> +
> + if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
> + dev_err(chdev, "Failed to get stream ID for channel %d\n",
> + tdc->id);
> + return -EINVAL;

Can you check similar problem before post patch, here also can use
return dev_err_probe()

Frank
> + }
> +
> + chan->dev->chan_dma_dev = true;
> + }
> +
> + /* program stream-id for this channel */
> + tegra_dma_program_sid(tdc, stream_id);
> + tdc->stream_id = stream_id;
> + }
> +
> ret = devm_of_dma_controller_register(&pdev->dev, pdev->dev.of_node,
> tegra_dma_of_xlate, tdma);
> if (ret < 0) {
> --
> 2.50.1
>