Re: [PATCH v4 4/4] media: nxp: Add dev_err_probe() to all error paths in *async_register() helpers

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Frank,

Thank you for the patch.

On Fri, Jan 16, 2026 at 11:29:22AM -0500, Frank Li wrote:
> Add dev_err_probe() to all error branches in the *async_register() helpers
> to provide clearer diagnostic information when device registration fails.
> 
> Drop the explicit error message after returning from
> mipi_csis_async_register(), as the error is already reported by this
> helper.
> 
> No functional change.

That's not quite exact, there are functional changes.

> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> change in v2
> - new patch
> ---
>  drivers/media/platform/nxp/imx-mipi-csis.c    | 31 ++++++++++++++++-----------
>  drivers/media/platform/nxp/imx8mq-mipi-csi2.c | 27 ++++++++++++++---------
>  2 files changed, 35 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index 9a43fd1eb0bcee7ac0c47f28ad89012de45a70d9..85098824f4917b3cda3aa71c4ed0a41939283e12 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -1359,18 +1359,18 @@ static int mipi_csis_async_register(struct mipi_csis_device *csis)
>  		fwnode_graph_get_endpoint_by_id(dev_fwnode(csis->dev), 0, 0,
>  						FWNODE_GRAPH_ENDPOINT_NEXT);
>  	if (!ep)
> -		return -ENOTCONN;
> +		return dev_err_probe(csis->dev, -ENOTCONN,
> +				     "failed to get remote endpoint\n");

It's not the remote endpoint, but the local endpoint.

>  
>  	ret = v4l2_fwnode_endpoint_parse(ep, &vep);
>  	if (ret)
> -		return ret;
> +		return dev_err_probe(csis->dev, ret,
> +				     "failed to parse endpoint\n");
>  
>  	for (i = 0; i < vep.bus.mipi_csi2.num_data_lanes; ++i) {
> -		if (vep.bus.mipi_csi2.data_lanes[i] != i + 1) {
> -			dev_err(csis->dev,
> -				"data lanes reordering is not supported");
> -			return -EINVAL;
> -		}
> +		if (vep.bus.mipi_csi2.data_lanes[i] != i + 1)
> +			return dev_err_probe(csis->dev, -EINVAL,
> +					     "data lanes reordering is not supported");

Missing \n

>  	}
>  
>  	csis->bus = vep.bus.mipi_csi2;
> @@ -1382,15 +1382,22 @@ static int mipi_csis_async_register(struct mipi_csis_device *csis)
>  	asd = v4l2_async_nf_add_fwnode_remote(&csis->notifier, ep,
>  					      struct v4l2_async_connection);
>  	if (IS_ERR(asd))
> -		return PTR_ERR(asd);
> +		return dev_err_probe(csis->dev, PTR_ERR(asd),
> +				     "failed to add remote fwmode to notifier\n");

s/fwmode/fwnode/

>  
>  	csis->notifier.ops = &mipi_csis_notify_ops;
>  
>  	ret = v4l2_async_nf_register(&csis->notifier);
>  	if (ret)
> -		return ret;
> +		return dev_err_probe(csis->dev, ret,
> +				     "failed to register notifier\n");
>  
> -	return v4l2_async_register_subdev(&csis->sd);
> +	ret = v4l2_async_register_subdev(&csis->sd);
> +	if (ret)
> +		return dev_err_probe(csis->dev, ret,
> +				     "failed to register subdev\n");
> +
> +	return 0;
>  }
>  
>  /* -----------------------------------------------------------------------------
> @@ -1549,10 +1556,8 @@ static int mipi_csis_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, &csis->sd);
>  
>  	ret = mipi_csis_async_register(csis);
> -	if (ret < 0) {
> -		dev_err(dev, "async register failed: %d\n", ret);
> +	if (ret < 0)
>  		goto err_cleanup;
> -	}
>  
>  	/* Initialize debugfs. */
>  	mipi_csis_debugfs_init(csis);
> diff --git a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> index 9d946b68cf59d9f4fb3413fc90219efd380d9d95..b3b9e9dc8a95c76628d573824c12f9391fb7b4a0 100644
> --- a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> +++ b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> @@ -727,18 +727,18 @@ static int imx8mq_mipi_csi_async_register(struct csi_state *state)
>  		fwnode_graph_get_endpoint_by_id(dev_fwnode(state->dev), 0, 0,
>  						FWNODE_GRAPH_ENDPOINT_NEXT);
>  	if (!ep)
> -		return -ENOTCONN;
> +		return dev_err_probe(state->dev, -ENOTCONN,
> +				     "failed to get remote endpoint fwnode\n");
>  
>  	ret = v4l2_fwnode_endpoint_parse(ep, &vep);
>  	if (ret)
> -		return ret;
> +		return dev_err_probe(state->dev, ret,
> +				     "failed parse endpoint fwnode\n");

I'd write

+				     "failed to parse endpoint\n");

to match the imx-mipi-csis.c driver.

>  
>  	for (i = 0; i < vep.bus.mipi_csi2.num_data_lanes; ++i) {
> -		if (vep.bus.mipi_csi2.data_lanes[i] != i + 1) {
> -			dev_err(state->dev,
> -				"data lanes reordering is not supported");
> -			return -EINVAL;
> -		}
> +		if (vep.bus.mipi_csi2.data_lanes[i] != i + 1)
> +			return dev_err_probe(state->dev, -EINVAL,
> +					     "data lanes reordering is not supported");
>  	}
>  
>  	state->bus = vep.bus.mipi_csi2;
> @@ -750,15 +750,22 @@ static int imx8mq_mipi_csi_async_register(struct csi_state *state)
>  	asd = v4l2_async_nf_add_fwnode_remote(&state->notifier, ep,
>  					      struct v4l2_async_connection);
>  	if (IS_ERR(asd))
> -		return PTR_ERR(asd);
> +		return dev_err_probe(state->dev, PTR_ERR(asd),
> +				     "failed add fwnode to notifier\n");

s/failed add/failed to add/

>  
>  	state->notifier.ops = &imx8mq_mipi_csi_notify_ops;
>  
>  	ret = v4l2_async_nf_register(&state->notifier);
>  	if (ret)
> -		return ret;
> +		return dev_err_probe(state->dev, ret,
> +				     "failed to register notifier\n");
>  
> -	return v4l2_async_register_subdev(&state->sd);
> +	ret = v4l2_async_register_subdev(&state->sd);
> +	if (ret)
> +		return dev_err_probe(state->dev, ret,
> +				     "failed to register subdev\n");
> +
> +	return 0;
>  }
>  
>  /* -----------------------------------------------------------------------------

-- 
Regards,

Laurent Pinchart