Re: [PATCH v5 22/24] v4l: subdev: add v4l2_subdev_get_format_dir()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the patch.

On Thu, Apr 15, 2021 at 04:04:48PM +0300, Tomi Valkeinen wrote:
> Add v4l2_subdev_get_format_dir() which can be used to find subdev format
> for a specific stream on a multiplexed pad. The function will follow the
> routes and links until it finds a non-multiplexed pad.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  drivers/media/v4l2-core/v4l2-subdev.c | 96 +++++++++++++++++++++++++++
>  include/media/v4l2-subdev.h           | 26 ++++++++
>  2 files changed, 122 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 7a4f71d8c6c3..430dbdaab080 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -998,6 +998,102 @@ bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_subdev_has_route);
>  
> +int v4l2_subdev_get_format_dir(struct media_pad *pad, u16 stream,
> +			       enum v4l2_direction dir,
> +			       struct v4l2_subdev_format *fmt)
> +{
> +	struct device *dev = pad->entity->graph_obj.mdev->dev;
> +	int ret;
> +	int i;
> +
> +	dev_dbg(dev, "%s '%s':%u:%u %s\n", __func__,
> +		pad->entity->name, pad->index, stream,
> +		dir == V4L2_DIR_SOURCEWARD ? "sourceward" : "sinkward");
> +
> +	while (true) {
> +		struct v4l2_subdev_krouting routing;
> +		struct v4l2_subdev_route *route;
> +
> +		if (pad->entity->obj_type != MEDIA_ENTITY_TYPE_V4L2_SUBDEV)
> +			return -EINVAL;
> +
> +		ret = v4l2_subdev_link_validate_get_format(pad, fmt);
> +		if (ret == 0)
> +			return 0;
> +		else if (ret != -ENOIOCTLCMD)
> +			return ret;
> +
> +		if (pad->flags &
> +		    (dir == V4L2_DIR_SINKWARD ? MEDIA_PAD_FL_SOURCE :
> +						MEDIA_PAD_FL_SINK)) {
> +			pad = media_entity_remote_pad(pad);
> +
> +			if (!pad)
> +				return -EINVAL;
> +
> +			if (pad->entity->obj_type != MEDIA_ENTITY_TYPE_V4L2_SUBDEV)
> +				return -EINVAL;
> +
> +			ret = v4l2_subdev_link_validate_get_format(pad, fmt);
> +			if (ret == 0)
> +				return 0;
> +			else if (ret != -ENOIOCTLCMD)
> +				return ret;
> +		}
> +
> +		ret = v4l2_subdev_get_krouting(media_entity_to_v4l2_subdev(pad->entity), &routing);
> +		if (ret)
> +			return ret;
> +
> +		route = NULL;
> +		for (i = 0; i < routing.num_routes; ++i) {
> +			u16 near_pad = dir == V4L2_DIR_SINKWARD ?
> +					       routing.routes[i].sink_pad :
> +					       routing.routes[i].source_pad;
> +			u16 near_stream = dir == V4L2_DIR_SINKWARD ?
> +						  routing.routes[i].sink_stream :
> +						  routing.routes[i].source_stream;
> +
> +			if (!(routing.routes[i].flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
> +				continue;
> +
> +			if (near_pad != pad->index)
> +				continue;
> +
> +			if (near_stream != stream)
> +				continue;
> +
> +			if (route) {
> +				dev_err(dev,
> +					"%s: '%s' has multiple active routes for stream %u\n",
> +					__func__, pad->entity->name, stream);
> +				v4l2_subdev_free_routing(&routing);
> +				return -EINVAL;
> +			}
> +
> +			route = &routing.routes[i];
> +		}
> +
> +		if (!route) {
> +			dev_err(dev, "%s: no route found in '%s' for stream %u\n",
> +				__func__, pad->entity->name, stream);
> +			v4l2_subdev_free_routing(&routing);
> +			return -EINVAL;
> +		}
> +
> +		if (dir == V4L2_DIR_SINKWARD) {
> +			pad = &pad->entity->pads[route->source_pad];
> +			stream = route->source_stream;
> +		} else {
> +			pad = &pad->entity->pads[route->sink_pad];
> +			stream = route->sink_stream;
> +		}
> +
> +		v4l2_subdev_free_routing(&routing);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_format_dir);
> +
>  int v4l2_subdev_link_validate(struct media_link *link)
>  {
>  	struct v4l2_subdev *sink;
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 1843b77dd843..730631f9a091 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -1239,4 +1239,30 @@ void v4l2_subdev_cpy_routing(struct v4l2_subdev_krouting *dst,
>  bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,
>  			   unsigned int pad0, unsigned int pad1);
>  
> +/**
> + * enum v4l2_direction - Direction either towards the source or the sink
> + *
> + * @V4L2_DIR_SOURCEWARD: Direction towards the source.
> + * @V4L2_DIR_SINKWARD: Direction towards the sink.
> + */
> +enum v4l2_direction {
> +	V4L2_DIR_SOURCEWARD,
> +	V4L2_DIR_SINKWARD,
> +};
> +
> +/**
> + * v4l2_subdev_get_format_dir() - Find format by following streams

The name is a bit cryptic, and the usage pattern error-prone. Can we do
better ?  In particular, if we could limit the usage of this function to
be called on a non-multiplexed pad, we could drop the stream argument.
Deducing the direction argument from the type of pad would also make the
API simpler.

> + * @pad: The pad from which to start the search
> + * @stream: The stream for which we want to find the format
> + * @dir: The direction of the search
> + * @fmt: Pointer to &struct v4l2_subdev_format where the found format is stored
> + *
> + * This function attempts to find v4l2_subdev_format for a specific stream on a
> + * multiplexed pad by following the stream using routes and links to the specified
> + * direction, until a non-multiplexed pad is found.
> + */
> +int v4l2_subdev_get_format_dir(struct media_pad *pad, u16 stream,
> +			       enum v4l2_direction dir,
> +			       struct v4l2_subdev_format *fmt);
> +
>  #endif

-- 
Regards,

Laurent Pinchart