[PATCH] media: imx: imx7-media-csi: Fix error handling in imx7_csi_async_register()

[PATCH] media: imx: imx7-media-csi: Fix error handling in imx7_csi_async_register()

[Frieder Schrempf]

From: Frieder Schrempf <frieder.schrempf@kontron.de>

If fwnode_graph_get_endpoint_by_id() fails and returns NULL, there is
no point in going on. Print an error message a abort instead.

Also we don't need to check for an existing asd. Any failure of
v4l2_async_nf_add_fwnode_remote() should abort the probe.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
 drivers/media/platform/nxp/imx7-media-csi.c | 22 +++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/media/platform/nxp/imx7-media-csi.c b/drivers/media/platform/nxp/imx7-media-csi.c
index 886374d3a6ff..a7db310624e2 100644
--- a/drivers/media/platform/nxp/imx7-media-csi.c
+++ b/drivers/media/platform/nxp/imx7-media-csi.c
@@ -2191,18 +2191,20 @@ static int imx7_csi_async_register(struct imx7_csi *csi)
 
 	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(csi->dev), 0, 0,
 					     FWNODE_GRAPH_ENDPOINT_NEXT);
-	if (ep) {
-		asd = v4l2_async_nf_add_fwnode_remote(&csi->notifier, ep,
-						      struct v4l2_async_subdev);
+	if (!ep) {
+		dev_err(csi->dev, "Failed to get remote endpoint\n");
+		return -ENOTCONN;
+	}
 
-		fwnode_handle_put(ep);
+	asd = v4l2_async_nf_add_fwnode_remote(&csi->notifier, ep,
+					      struct v4l2_async_subdev);
 
-		if (IS_ERR(asd)) {
-			ret = PTR_ERR(asd);
-			/* OK if asd already exists */
-			if (ret != -EEXIST)
-				return ret;
-		}
+	fwnode_handle_put(ep);
+
+	if (IS_ERR(asd)) {
+		ret = PTR_ERR(asd);
+		dev_err(csi->dev, "Failed to add remote subdev to notifier: %d\n", ret);
+		return ret;
 	}
 
 	csi->notifier.ops = &imx7_csi_notify_ops;
-- 
2.39.1

Re: [PATCH] media: imx: imx7-media-csi: Fix error handling in imx7_csi_async_register()

[Laurent Pinchart]

Hi Frieder,

Thank you for the patch.

On Tue, Feb 14, 2023 at 05:31:56PM +0100, Frieder Schrempf wrote:
> From: Frieder Schrempf <frieder.schrempf@kontron.de>
> 
> If fwnode_graph_get_endpoint_by_id() fails and returns NULL, there is
> no point in going on. Print an error message a abort instead.

s/a abort/and abort/

Explaining why as a reference to future readers would be nice:

The CSI requires a connected source subdev to operate. If
fwnode_graph_get_endpoint_by_id() fails and returns NULL, there is no
point in going on. Print an error message and abort instead.

> Also we don't need to check for an existing asd. Any failure of
> v4l2_async_nf_add_fwnode_remote() should abort the probe.
> 
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
>  drivers/media/platform/nxp/imx7-media-csi.c | 22 +++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/platform/nxp/imx7-media-csi.c b/drivers/media/platform/nxp/imx7-media-csi.c
> index 886374d3a6ff..a7db310624e2 100644
> --- a/drivers/media/platform/nxp/imx7-media-csi.c
> +++ b/drivers/media/platform/nxp/imx7-media-csi.c
> @@ -2191,18 +2191,20 @@ static int imx7_csi_async_register(struct imx7_csi *csi)
>  
>  	ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(csi->dev), 0, 0,
>  					     FWNODE_GRAPH_ENDPOINT_NEXT);
> -	if (ep) {
> -		asd = v4l2_async_nf_add_fwnode_remote(&csi->notifier, ep,
> -						      struct v4l2_async_subdev);
> +	if (!ep) {
> +		dev_err(csi->dev, "Failed to get remote endpoint\n");

Let's use dev_err_probe() as this is called from the probe function:

		dev_err_probe(csi->dev, -ENOTCONN,
			      "Failed to get remote endpoint\n");

> +		return -ENOTCONN;
> +	}
>  
> -		fwnode_handle_put(ep);
> +	asd = v4l2_async_nf_add_fwnode_remote(&csi->notifier, ep,
> +					      struct v4l2_async_subdev);
>  
> -		if (IS_ERR(asd)) {
> -			ret = PTR_ERR(asd);
> -			/* OK if asd already exists */
> -			if (ret != -EEXIST)
> -				return ret;
> -		}
> +	fwnode_handle_put(ep);
> +
> +	if (IS_ERR(asd)) {
> +		ret = PTR_ERR(asd);
> +		dev_err(csi->dev, "Failed to add remote subdev to notifier: %d\n", ret);

Same here:

		dev_err_probe(csi->dev, ret,
			      "Failed to add remote subdev to notifier\n");

> +		return ret;
>  	}
>  
>  	csi->notifier.ops = &imx7_csi_notify_ops;

-- 
Regards,

Laurent Pinchart