linux-kernel - Re: [PATCH v3 1/2] media: i2c: ov772x: Add support for BT656 mode

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Date:   Fri, 4 Sep 2020 04:20:00 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Jacopo Mondi <jacopo@...ndi.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@....fi>,
        Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        Biju Das <biju.das.jz@...renesas.com>,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH v3 1/2] media: i2c: ov772x: Add support for BT656 mode

Hi Prabhakar,

Thank you for the patch.

On Mon, Aug 24, 2020 at 08:04:05PM +0100, Lad Prabhakar wrote:
> Add support to read the bus-type and enable BT656 mode if needed.
> 
> Also fail probe if unsupported bus_type is detected.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@...renesas.com>
> ---
>  drivers/media/i2c/ov772x.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
> index 2cc6a678069a..67764d647526 100644
> --- a/drivers/media/i2c/ov772x.c
> +++ b/drivers/media/i2c/ov772x.c
> @@ -31,6 +31,7 @@
>  #include <media/v4l2-ctrls.h>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-event.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-image-sizes.h>
>  #include <media/v4l2-subdev.h>
>  
> @@ -434,6 +435,7 @@ struct ov772x_priv {
>  #ifdef CONFIG_MEDIA_CONTROLLER
>  	struct media_pad pad;
>  #endif
> +	struct v4l2_fwnode_endpoint ep;
>  };
>  
>  /*
> @@ -581,6 +583,13 @@ static int ov772x_s_stream(struct v4l2_subdev *sd, int enable)
>  	if (priv->streaming == enable)
>  		goto done;
>  
> +	if (priv->ep.bus_type == V4L2_MBUS_BT656) {
> +		ret = regmap_update_bits(priv->regmap, COM7, ITU656_ON_OFF,
> +					 enable ? ITU656_ON_OFF : ~ITU656_ON_OFF);
> +		if (ret)
> +			goto done;
> +	}
> +
>  	ret = regmap_update_bits(priv->regmap, COM2, SOFT_SLEEP_MODE,
>  				 enable ? 0 : SOFT_SLEEP_MODE);
>  	if (ret)
> @@ -1354,6 +1363,7 @@ static const struct v4l2_subdev_ops ov772x_subdev_ops = {
>  
>  static int ov772x_probe(struct i2c_client *client)
>  {
> +	struct fwnode_handle *endpoint;
>  	struct ov772x_priv	*priv;
>  	int			ret;
>  	static const struct regmap_config ov772x_regmap_config = {
> @@ -1415,6 +1425,28 @@ static int ov772x_probe(struct i2c_client *client)
>  		goto error_clk_put;
>  	}
>  
> +	endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev),
> +						  NULL);
> +	if (!endpoint) {
> +		dev_err(&client->dev, "endpoint node not found\n");
> +		ret = -EINVAL;
> +		goto error_clk_put;
> +	}
> +
> +	ret = v4l2_fwnode_endpoint_parse(endpoint, &priv->ep);

v4l2_fwnode_endpoint_parse() is deprecated for new drivers,
v4l2_fwnode_endpoint_alloc_parse() is recommended instead. Please note
that v4l2_fwnode_endpoint_free() then needs to be called in the error
path and in remove().

On the other hand, not setting .bus_type and letting the parse()
function determine the but type automatically is also deprecated, and I
don't think forcing drivers to call v4l2_fwnode_endpoint_alloc_parse()
once for each bus type until one succeeds is a good API. As change will
be needed in that API, you can ignore v4l2_fwnode_endpoint_alloc_parse()
for the time being if you want.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> +	fwnode_handle_put(endpoint);
> +	if (ret) {
> +		dev_err(&client->dev, "Could not parse endpoint\n");
> +		goto error_clk_put;
> +	}
> +
> +	if (priv->ep.bus_type != V4L2_MBUS_PARALLEL &&
> +	    priv->ep.bus_type != V4L2_MBUS_BT656) {
> +		dev_err(&client->dev, "Unsupported bus type %d\n",
> +			priv->ep.bus_type);
> +		goto error_clk_put;
> +	}
> +
>  	ret = ov772x_video_probe(priv);
>  	if (ret < 0)
>  		goto error_gpio_put;

-- 
Regards,

Laurent Pinchart