linux-kernel - Re: [PATCH 2/2] media: i2c: imx274: implement fwnode parsing

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Date:   Tue, 23 Nov 2021 13:23:24 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Eugen Hristev <eugen.hristev@...rochip.com>
Cc:     leonl@...pardimaging.com, linux-media@...r.kernel.org,
        skomatineni@...dia.com, luca@...aceresoli.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] media: i2c: imx274: implement fwnode parsing

Hi Eugen,

On Tue, Nov 23, 2021 at 01:15:21PM +0200, Eugen Hristev wrote:
> Implement fwnode parsing at probe time.
> Check if the bus and number of lanes are supported.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
> ---
>  drivers/media/i2c/imx274.c | 40 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c
> index e31f006b10d9..774912f44efe 100644
> --- a/drivers/media/i2c/imx274.c
> +++ b/drivers/media/i2c/imx274.c
> @@ -27,6 +27,7 @@
>  
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
>  /*
> @@ -1957,6 +1958,41 @@ static const struct i2c_device_id imx274_id[] = {
>  };
>  MODULE_DEVICE_TABLE(i2c, imx274_id);
>  
> +static int imx274_fwnode_parse(struct device *dev)
> +{
> +	struct fwnode_handle *endpoint;
> +	/* Only CSI2 is supported */
> +	struct v4l2_fwnode_endpoint ep = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY
> +	};
> +	int ret;
> +
> +	endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(dev), NULL);
> +	if (!endpoint) {
> +		dev_err(dev, "Endpoint node not found\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = v4l2_fwnode_endpoint_alloc_parse(endpoint, &ep);

This allocates memory for the link frequencies. It needs to be released at
some point.

You could also use v4l1_fwnode_endpoint_parse() as the driver doesn't seem
to use link frequencies (albeit it probably should, but that's another
discussion).

> +	fwnode_handle_put(endpoint);
> +	if (ret == -ENXIO) {
> +		dev_err(dev, "Unsupported bus type, should be CSI2\n");
> +		return ret;
> +	} else if (ret) {
> +		dev_err(dev, "Parsing endpoint node failed %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Check number of data lanes, only 4 lanes supported */
> +	if (ep.bus.mipi_csi2.num_data_lanes != 4) {
> +		dev_err(dev, "Invalid data lanes: %d\n",
> +			ep.bus.mipi_csi2.num_data_lanes);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static int imx274_probe(struct i2c_client *client)
>  {
>  	struct v4l2_subdev *sd;
> @@ -1971,6 +2007,10 @@ static int imx274_probe(struct i2c_client *client)
>  
>  	mutex_init(&imx274->lock);
>  
> +	ret = imx274_fwnode_parse(dev);
> +	if (ret)
> +		return ret;
> +
>  	imx274->inck = devm_clk_get_optional(dev, "inck");
>  	if (IS_ERR(imx274->inck))
>  		return PTR_ERR(imx274->inck);

-- 
Kind regards,

Sakari Ailus