Re: [PATCH v2 2/6] media: nxp: imx8-isi: Add stream ID validation for crossbar routing

[Frank Li]

On Mon, Jul 20, 2026 at 11:34:04AM +0800, Guoniu Zhou wrote:
> Add validation to enforce hardware constraints that were previously
> missing in the crossbar routing configuration:
>
> - SOURCE stream must be 0 (ISI pipes are hardcoded to stream 0)
>
> This check complements the existing memory input validation and ensures
> that all routing configurations respect hardware limitations.
>
> Signed-off-by: Guoniu Zhou <guoniu.zhou@xxxxxxxxxxx>
> ---
> Changes in v2:
> - New patch split from v1 1/5: adds stream ID validation on top of
>   for_each_active_route() fix (Frank Li)
> - Remove incorrect sink_stream validation
> ---
>  drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> index 84871bceb31d..328d08a278ea 100644
> --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> @@ -106,8 +106,20 @@ static int __mxc_isi_crossbar_set_routing(struct v4l2_subdev *sd,
>  	if (ret)
>  		return ret;
>
> -	/* The memory input can be routed to the first pipeline only. */
> +	/*
> +	 * Validate routes against hardware constraints:
> +	 * - SOURCE stream must be 0 (pipes are hardcoded to stream 0)
> +	 * - Memory input can only route to the first pipeline
> +	 */
>  	for_each_active_route(routing, route) {
> +		if (route->source_stream != 0) {
> +			dev_dbg(xbar->isi->dev,

it is one error, should be dev_err()?

Frank
> +				"route to pipe %u must use source_stream=0, got %u\n",
> +				route->source_pad - xbar->num_sinks,
> +				route->source_stream);
> +			return -ENXIO;
> +		}
> +
>  		if (route->sink_pad == xbar->num_sinks - 1 &&
>  		    route->source_pad != xbar->num_sinks) {
>  			dev_dbg(xbar->isi->dev,
>
> --
> 2.34.1
>
>