Re: [PATCH v3 06/13] media: platform: video-mux: Register a subdev notifier

[Hans Verkuil <hverkuil@xs4all.nl>]

On 03/21/18 01:37, Steve Longerbeam wrote:
> Parse neighbor remote devices on the video muxes input ports, add them to a
> subdev notifier, and register the subdev notifier for the video mux, by
> calling v4l2_async_register_fwnode_subdev().
> 
> Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
> ---
> Changes since v2:
> - none
> Changes since v1:
> - add #include <linux/slab.h> for kcalloc() declaration.
> ---
>  drivers/media/platform/video-mux.c | 36 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/video-mux.c b/drivers/media/platform/video-mux.c
> index ee89ad7..b93b0af 100644
> --- a/drivers/media/platform/video-mux.c
> +++ b/drivers/media/platform/video-mux.c
> @@ -21,8 +21,10 @@
>  #include <linux/of.h>
>  #include <linux/of_graph.h>
>  #include <linux/platform_device.h>
> +#include <linux/slab.h>
>  #include <media/v4l2-async.h>
>  #include <media/v4l2-device.h>
> +#include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
>  struct video_mux {
> @@ -193,6 +195,38 @@ static const struct v4l2_subdev_ops video_mux_subdev_ops = {
>  	.video = &video_mux_subdev_video_ops,
>  };
>  
> +static int video_mux_parse_endpoint(struct device *dev,
> +				    struct v4l2_fwnode_endpoint *vep,
> +				    struct v4l2_async_subdev *asd)
> +{
> +	/*
> +	 * it's not an error if remote is missing on a video-mux
> +	 * input port, return -ENOTCONN to skip this endpoint with
> +	 * no error.
> +	 */
> +	return fwnode_device_is_available(asd->match.fwnode) ? 0 : -ENOTCONN;
> +}
> +
> +static int video_mux_async_register(struct video_mux *vmux,
> +				    unsigned int num_pads)
> +{
> +	unsigned int i, *ports;
> +	int ret;
> +
> +	ports = kcalloc(num_pads - 1, sizeof(*ports), GFP_KERNEL);
> +	if (!ports)
> +		return -ENOMEM;
> +	for (i = 0; i < num_pads - 1; i++)
> +		ports[i] = i;
> +
> +	ret = v4l2_async_register_fwnode_subdev(
> +		&vmux->subdev, sizeof(struct v4l2_async_subdev),
> +		ports, num_pads - 1, video_mux_parse_endpoint);
> +
> +	kfree(ports);
> +	return ret;
> +}
> +
>  static int video_mux_probe(struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> @@ -258,7 +292,7 @@ static int video_mux_probe(struct platform_device *pdev)
>  
>  	vmux->subdev.entity.ops = &video_mux_ops;
>  
> -	return v4l2_async_register_subdev(&vmux->subdev);
> +	return video_mux_async_register(vmux, num_pads);

I would prefer to change the last argument to 'num_pads - 1' and drop the ' - 1'
part in the video_mux_async_register() function. Perhaps renaming the num_pads
argument there to num_input_pads.

Regards,

	Hans

>  }
>  
>  static int video_mux_remove(struct platform_device *pdev)
>