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

[Frank Li]

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@xxxxxxxxxx>
> ---
...
>
> +	/*
> +	 * 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
>