linux-kernel - Re: [PATCH] media: imx: imx7-media-csi: Fix error handling in imx7_csi_async

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Message-ID: <Y+v9Fu5LNk5udjgB@pendragon.ideasonboard.com>
Date:   Tue, 14 Feb 2023 23:28:54 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Frieder Schrempf <frieder@...s.de>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rui Miguel Silva <rmfrfs@...il.com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Paul Elder <paul.elder@...asonboard.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH] media: imx: imx7-media-csi: Fix error handling in
 imx7_csi_async_register()

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@...tron.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@...asonboard.com>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.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