[v12,26/30] media: v4l2-subdev: Add v4l2_subdev_state_xlate_streams() helper

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Add a helper function to translate streams between two pads of a subdev,
using the subdev's internal routing table.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 26 ++++++++++++++++++++++++++
 include/media/v4l2-subdev.h           | 23 +++++++++++++++++++++++
 2 files changed, 49 insertions(+)

Moi,

On Wed, Jul 27, 2022 at 01:36:35PM +0300, Tomi Valkeinen wrote:
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Add a helper function to translate streams between two pads of a subdev,
> using the subdev's internal routing table.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  drivers/media/v4l2-core/v4l2-subdev.c | 26 ++++++++++++++++++++++++++
>  include/media/v4l2-subdev.h           | 23 +++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 2fc999b1b6c1..35ddf4dbe3a9 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -1619,6 +1619,32 @@ v4l2_subdev_state_get_opposite_stream_format(struct v4l2_subdev_state *state,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_opposite_stream_format);
>  
> +u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
> +				    u32 pad0, u32 pad1, u64 *streams)
> +{
> +	const struct v4l2_subdev_krouting *routing = &state->routing;
> +	struct v4l2_subdev_route *route;
> +	u64 streams0 = 0;
> +	u64 streams1 = 0;
> +
> +	for_each_active_route(routing, route) {
> +		if (route->sink_pad == pad0 && route->source_pad == pad1 &&
> +		    (*streams & BIT_ULL(route->sink_stream))) {
> +			streams0 |= BIT_ULL(route->sink_stream);
> +			streams1 |= BIT_ULL(route->source_stream);
> +		}
> +		if (route->source_pad == pad0 && route->sink_pad == pad1 &&
> +		    (*streams & BIT_ULL(route->source_stream))) {
> +			streams0 |= BIT_ULL(route->source_stream);
> +			streams1 |= BIT_ULL(route->sink_stream);
> +		}
> +	}
> +
> +	*streams = streams0;
> +	return streams1;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_state_xlate_streams);
> +
>  int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
>  				 const struct v4l2_subdev_krouting *routing,
>  				 enum v4l2_subdev_routing_restriction disallow)
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index f749effadde2..dd5cccc827ef 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -1554,6 +1554,29 @@ struct v4l2_mbus_framefmt *
>  v4l2_subdev_state_get_opposite_stream_format(struct v4l2_subdev_state *state,
>  					     u32 pad, u32 stream);
>  
> +/**
> + * v4l2_subdev_state_xlate_streams() - Translate streams from one pad to another
> + *
> + * @state: Subdevice state
> + * @pad0: The first pad
> + * @pad1: The second pad
> + * @streams: Streams bitmask on the first pad
> + *
> + * Streams on sink pads of a subdev are routed to source pads as expressed in
> + * the subdev state routing table. Stream numbers don't necessarily match on
> + * the sink and source side of a route. This function translates stream numbers
> + * on @pad0, expressed as a bitmask in @streams, to the corresponding streams
> + * on @pad1 using the routing table from the @state. It returns the stream mask
> + * on @pad1, and updates @streams with the streams that have been found in the
> + * routing table.
> + *
> + * @pad0 and @pad1 must be a sink and a source, in any order.
> + *
> + * Return: The bitmask of streams of @pad1 that are routed to @streams on @pad0.
> + */
> +u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
> +				    u32 pad0, u32 pad1, u64 *streams);
> +
>  /**
>   * enum v4l2_subdev_routing_restriction - Subdevice internal routing restrictions
>   *

How and where is this meant to be used?

Hi,

On 01/08/2022 15:37, Sakari Ailus wrote:

>> +u64 v4l2_subdev_state_xlate_streams(const struct v4l2_subdev_state *state,
>> +				    u32 pad0, u32 pad1, u64 *streams);
>> +
>>   /**
>>    * enum v4l2_subdev_routing_restriction - Subdevice internal routing restrictions
>>    *
> 
> How and where is this meant to be used?

I use it in subdev driver's .enable_streams(). E.g.:

static int ub953_enable_streams(struct v4l2_subdev *sd,
				struct v4l2_subdev_state *state, u32 pad,
				u64 streams_mask)
{
	struct ub953_data *priv = sd_to_ub953(sd);
	struct media_pad *remote_pad;
	u64 sink_streams;
	int ret;

	if (streams_mask & priv->enabled_source_streams)
		return -EALREADY;

	sink_streams = v4l2_subdev_state_xlate_streams(
		state, UB953_PAD_SOURCE, UB953_PAD_SINK, &streams_mask);

	remote_pad = media_entity_remote_pad(&priv->pads[UB953_PAD_SINK]);

	ret = v4l2_subdev_enable_streams(priv->source_sd, remote_pad->index,
					 sink_streams);
	if (ret)
		return ret;

	priv->enabled_source_streams |= streams_mask;

	return 0;
}

The driver gets the source pad & stream mask, and must get the
sink pad & stream mask so that it can then call enable_streams
on its source subdev.

  Tomi