linux-kernel - Re: [PATCH v5 17/39] [media] v4l2-mc: add a function to inherit controls from a pipeline

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Message-ID: <5f999fec-5008-7092-1d7f-4c3d12120ace@xs4all.nl>
Date:   Fri, 10 Mar 2017 12:45:18 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Steve Longerbeam <slongerbeam@...il.com>, robh+dt@...nel.org,
        mark.rutland@....com, shawnguo@...nel.org, kernel@...gutronix.de,
        fabio.estevam@....com, linux@...linux.org.uk, mchehab@...nel.org,
        nick@...anahar.org, markus.heiser@...marIT.de,
        p.zabel@...gutronix.de, laurent.pinchart+renesas@...asonboard.com,
        bparrot@...com, geert@...ux-m68k.org, arnd@...db.de,
        sudipm.mukherjee@...il.com, minghsiu.tsai@...iatek.com,
        tiffany.lin@...iatek.com, jean-christophe.trotin@...com,
        horms+renesas@...ge.net.au, niklas.soderlund+renesas@...natech.se,
        robert.jarzmik@...e.fr, songjun.wu@...rochip.com,
        andrew-ct.chen@...iatek.com, gregkh@...uxfoundation.org,
        shuah@...nel.org, sakari.ailus@...ux.intel.com, pavel@....cz
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        devel@...verdev.osuosl.org,
        Steve Longerbeam <steve_longerbeam@...tor.com>
Subject: Re: [PATCH v5 17/39] [media] v4l2-mc: add a function to inherit
 controls from a pipeline

On 10/03/17 05:52, Steve Longerbeam wrote:
> v4l2_pipeline_inherit_controls() will add the v4l2 controls from
> all subdev entities in a pipeline to a given video device.
> 
> Signed-off-by: Steve Longerbeam <steve_longerbeam@...tor.com>
> ---
>  drivers/media/v4l2-core/v4l2-mc.c | 48 +++++++++++++++++++++++++++++++++++++++
>  include/media/v4l2-mc.h           | 25 ++++++++++++++++++++
>  2 files changed, 73 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> index 303980b..09d4d97 100644
> --- a/drivers/media/v4l2-core/v4l2-mc.c
> +++ b/drivers/media/v4l2-core/v4l2-mc.c
> @@ -22,6 +22,7 @@
>  #include <linux/usb.h>
>  #include <media/media-device.h>
>  #include <media/media-entity.h>
> +#include <media/v4l2-ctrls.h>
>  #include <media/v4l2-fh.h>
>  #include <media/v4l2-mc.h>
>  #include <media/v4l2-subdev.h>
> @@ -238,6 +239,53 @@ int v4l_vb2q_enable_media_source(struct vb2_queue *q)
>  }
>  EXPORT_SYMBOL_GPL(v4l_vb2q_enable_media_source);
>  
> +int __v4l2_pipeline_inherit_controls(struct video_device *vfd,
> +				     struct media_entity *start_entity)
> +{
> +	struct media_device *mdev = start_entity->graph_obj.mdev;
> +	struct media_entity *entity;
> +	struct media_graph graph;
> +	struct v4l2_subdev *sd;
> +	int ret;
> +
> +	ret = media_graph_walk_init(&graph, mdev);
> +	if (ret)
> +		return ret;
> +
> +	media_graph_walk_start(&graph, start_entity);
> +
> +	while ((entity = media_graph_walk_next(&graph))) {
> +		if (!is_media_entity_v4l2_subdev(entity))
> +			continue;
> +
> +		sd = media_entity_to_v4l2_subdev(entity);
> +
> +		ret = v4l2_ctrl_add_handler(vfd->ctrl_handler,
> +					    sd->ctrl_handler,
> +					    NULL);
> +		if (ret)
> +			break;
> +	}
> +
> +	media_graph_walk_cleanup(&graph);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(__v4l2_pipeline_inherit_controls);
> +
> +int v4l2_pipeline_inherit_controls(struct video_device *vfd,
> +				   struct media_entity *start_entity)
> +{
> +	struct media_device *mdev = start_entity->graph_obj.mdev;
> +	int ret;
> +
> +	mutex_lock(&mdev->graph_mutex);
> +	ret = __v4l2_pipeline_inherit_controls(vfd, start_entity);
> +	mutex_unlock(&mdev->graph_mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_pipeline_inherit_controls);
> +
>  /* -----------------------------------------------------------------------------
>   * Pipeline power management
>   *
> diff --git a/include/media/v4l2-mc.h b/include/media/v4l2-mc.h
> index 2634d9d..9848e77 100644
> --- a/include/media/v4l2-mc.h
> +++ b/include/media/v4l2-mc.h
> @@ -171,6 +171,17 @@ void v4l_disable_media_source(struct video_device *vdev);
>   */
>  int v4l_vb2q_enable_media_source(struct vb2_queue *q);
>  
> +/**
> + * v4l2_pipeline_inherit_controls - Add the v4l2 controls from all
> + *				    subdev entities in a pipeline to
> + *				    the given video device.
> + * @vfd: the video device
> + * @start_entity: Starting entity
> + */
> +int __v4l2_pipeline_inherit_controls(struct video_device *vfd,
> +				     struct media_entity *start_entity);
> +int v4l2_pipeline_inherit_controls(struct video_device *vfd,
> +				   struct media_entity *start_entity);

Please document which is the unlocked variant and which lock the locked
variant takes.

Regards,

	Hans

>  
>  /**
>   * v4l2_pipeline_pm_use - Update the use count of an entity
> @@ -231,6 +242,20 @@ static inline int v4l_vb2q_enable_media_source(struct vb2_queue *q)
>  	return 0;
>  }
>  
> +static inline int __v4l2_pipeline_inherit_controls(
> +	struct video_device *vfd,
> +	struct media_entity *start_entity)
> +{
> +	return 0;
> +}
> +
> +static inline int v4l2_pipeline_inherit_controls(
> +	struct video_device *vfd,
> +	struct media_entity *start_entity)
> +{
> +	return 0;
> +}
> +
>  static inline int v4l2_pipeline_pm_use(struct media_entity *entity, int use)
>  {
>  	return 0;
>