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Message-ID: <d2432381-827f-4825-a450-9954f8291576@foss.st.com>
Date: Mon, 29 Apr 2024 10:52:34 +0200
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Subject: Re: [PATCH linux-next] media: i2c: st-mipid02: replace of_node_put()
 with __free
To: R Sundar <prosunofficial@gmail.com>, <sylvain.petinot@foss.st.com>,
        <mchehab@kernel.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Sakari Ailus <sakari.ailus@linux.intel.com>
CC: <linux-media@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <skhan@linuxfoundation.org>, <javier.carrasco.cruz@gmail.com>,
        Julia Lawall
	<julia.lawall@inria.fr>
References: <20240427095643.11486-1-prosunofficial@gmail.com>
Content-Language: en-US
From: Benjamin Mugnier <benjamin.mugnier@foss.st.com>
In-Reply-To: <20240427095643.11486-1-prosunofficial@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit

Hi,

Thank you for your patch.

On 4/27/24 11:56, R Sundar wrote:
> Use the new cleanup magic to replace of_node_put() with
> __free(device_node) marking to auto release and to simplify the error
> paths.
> 
> Suggested-by: Julia Lawall <julia.lawall@inria.fr>
> Signed-off-by: R Sundar <prosunofficial@gmail.com>

I was not aware of this kind of auto release mechanism. Thanks for
bringing that to my eyes.

Now I looked in /drivers/media and couldn't find such structure. All
drivers seem to follow the goto error_of_node_put style.
As I'm unsure if we want to introduce such magic, could either Laurent
or Sakari comment on this ?

> ---
>  drivers/media/i2c/st-mipid02.c | 37 +++++++++-------------------------
>  1 file changed, 9 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/media/i2c/st-mipid02.c b/drivers/media/i2c/st-mipid02.c
> index f250640729ca..d42a306530f3 100644
> --- a/drivers/media/i2c/st-mipid02.c
> +++ b/drivers/media/i2c/st-mipid02.c
> @@ -715,31 +715,28 @@ static int mipid02_parse_rx_ep(struct mipid02_dev *bridge)
>  	struct v4l2_fwnode_endpoint ep = { .bus_type = V4L2_MBUS_CSI2_DPHY };
>  	struct i2c_client *client = bridge->i2c_client;
>  	struct v4l2_async_connection *asd;
> -	struct device_node *ep_node;
>  	int ret;
>  
>  	/* parse rx (endpoint 0) */
> -	ep_node = of_graph_get_endpoint_by_regs(bridge->i2c_client->dev.of_node,
> -						0, 0);
> +	struct device_node *ep_node __free(device_node) =
> +		of_graph_get_endpoint_by_regs(bridge->i2c_client->dev.of_node, 0, 0);
>  	if (!ep_node) {
>  		dev_err(&client->dev, "unable to find port0 ep");
> -		ret = -EINVAL;
> -		goto error;
> +		return -EINVAL;
>  	}
>  
>  	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep_node), &ep);
>  	if (ret) {
>  		dev_err(&client->dev, "Could not parse v4l2 endpoint %d\n",
>  			ret);
> -		goto error_of_node_put;
> +		return ret;
>  	}
>  
>  	/* do some sanity checks */
>  	if (ep.bus.mipi_csi2.num_data_lanes > 2) {
>  		dev_err(&client->dev, "max supported data lanes is 2 / got %d",
>  			ep.bus.mipi_csi2.num_data_lanes);
> -		ret = -EINVAL;
> -		goto error_of_node_put;
> +		return -EINVAL;
>  	}
>  
>  	/* register it for later use */
> @@ -750,7 +747,6 @@ static int mipid02_parse_rx_ep(struct mipid02_dev *bridge)
>  	asd = v4l2_async_nf_add_fwnode_remote(&bridge->notifier,
>  					      of_fwnode_handle(ep_node),
>  					      struct v4l2_async_connection);
> -	of_node_put(ep_node);
>  
>  	if (IS_ERR(asd)) {
>  		dev_err(&client->dev, "fail to register asd to notifier %ld",
> @@ -764,46 +760,31 @@ static int mipid02_parse_rx_ep(struct mipid02_dev *bridge)
>  		v4l2_async_nf_cleanup(&bridge->notifier);
>  
>  	return ret;
> -
> -error_of_node_put:
> -	of_node_put(ep_node);
> -error:
> -
> -	return ret;
>  }
>  
>  static int mipid02_parse_tx_ep(struct mipid02_dev *bridge)
>  {
>  	struct v4l2_fwnode_endpoint ep = { .bus_type = V4L2_MBUS_PARALLEL };
>  	struct i2c_client *client = bridge->i2c_client;
> -	struct device_node *ep_node;
>  	int ret;
>  
>  	/* parse tx (endpoint 2) */
> -	ep_node = of_graph_get_endpoint_by_regs(bridge->i2c_client->dev.of_node,
> -						2, 0);
> +	struct device_node *ep_node =
> +		of_graph_get_endpoint_by_regs(bridge->i2c_client->dev.of_node, 2, 0);

Shouldn't there be a '__free' here too ?

>  	if (!ep_node) {
>  		dev_err(&client->dev, "unable to find port1 ep");
> -		ret = -EINVAL;
> -		goto error;
> +		return -EINVAL;
>  	}
>  
>  	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep_node), &ep);
>  	if (ret) {
>  		dev_err(&client->dev, "Could not parse v4l2 endpoint\n");
> -		goto error_of_node_put;
> +		return ret;
>  	}
>  
> -	of_node_put(ep_node);
>  	bridge->tx = ep;
>  
>  	return 0;
> -
> -error_of_node_put:
> -	of_node_put(ep_node);
> -error:
> -
> -	return -EINVAL;
>  }
>  
>  static int mipid02_probe(struct i2c_client *client)

-- 
Regards,

Benjamin