[v7,03/27] media: entity: Walk the graph based on pads

Message ID	20210524104408.599645-4-tomi.valkeinen@ideasonboard.com
State	Superseded
Headers	show Return-Path: <linux-media-owner@kernel.org> From: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> To: linux-media@vger.kernel.org, sakari.ailus@linux.intel.com, Jacopo Mondi <jacopo+renesas@jmondi.org>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, niklas.soderlund+renesas@ragnatech.se Cc: Mauro Carvalho Chehab <mchehab@kernel.org>, Hans Verkuil <hverkuil-cisco@xs4all.nl>, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>, Pratyush Yadav <p.yadav@ti.com>, Lokesh Vutla <lokeshvutla@ti.com> Subject: [PATCH v7 03/27] media: entity: Walk the graph based on pads Date: Mon, 24 May 2021 13:43:44 +0300 Message-Id: <20210524104408.599645-4-tomi.valkeinen@ideasonboard.com> In-Reply-To: <20210524104408.599645-1-tomi.valkeinen@ideasonboard.com> References: <20210524104408.599645-1-tomi.valkeinen@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	v4l: subdev internal routing and streams \| expand [v7,00/27] v4l: subdev internal routing and streams [v7,01/27] media: entity: Use pad as a starting point for graph walk [v7,02/27] media: entity: Use pads instead of entities in the media graph walk stack [v7,03/27] media: entity: Walk the graph based on pads [v7,04/27] v4l: mc: Start walk from a specific pad in use count calculation [v7,05/27] media: entity: Add iterator helper for entity pads [v7,06/27] media: entity: Move the pipeline from entity to pads [v7,07/27] media: entity: Use pad as the starting point for a pipeline [v7,08/27] media: entity: Add has_route entity operation [v7,09/27] media: entity: Add media_entity_has_route() function [v7,10/27] media: entity: Use routing information during graph traversal [v7,11/27] media: entity: Skip link validation for pads to which there is no route [v7,12/27] media: entity: Add an iterator helper for connected pads [v7,13/27] media: entity: Add only connected pads to the pipeline [v7,14/27] media: entity: Add debug information in graph walk route check [v7,15/27] v4l: Add bus type to frame descriptors [v7,16/27] v4l: Add CSI-2 bus configuration to frame descriptors [v7,17/27] v4l: Add stream to frame descriptor [v7,18/27] media: Documentation: Add GS_ROUTING documentation [v7,19/27] v4l: subdev: Add [GS]_ROUTING subdev ioctls and operations [v7,20/27] v4l: subdev: add V4L2_SUBDEV_ROUTE_FL_SOURCE [v7,21/27] v4l: subdev: routing kernel helper functions [v7,22/27] v4l: subdev: add stream based configuration [v7,23/27] v4l: subdev: add 'stream' to subdev ioctls [v7,24/27] v4l: subdev: use streams in v4l2_subdev_link_validate() [v7,25/27] v4l: subdev: add routing & stream config to v4l2_subdev_state [v7,26/27] v4l: subdev: add V4L2_SUBDEV_FL_MULTIPLEXED [v7,27/27] v4l: subdev: increase V4L2_FRAME_DESC_ENTRY_MAX to 8

Message ID

20210524104408.599645-4-tomi.valkeinen@ideasonboard.com

State

Superseded

Headers

From: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
To: linux-media@vger.kernel.org, sakari.ailus@linux.intel.com,
	Jacopo Mondi <jacopo+renesas@jmondi.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	niklas.soderlund+renesas@ragnatech.se
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Hans Verkuil <hverkuil-cisco@xs4all.nl>,
	Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
	Pratyush Yadav <p.yadav@ti.com>, Lokesh Vutla <lokeshvutla@ti.com>
Subject: [PATCH v7 03/27] media: entity: Walk the graph based on pads
Date: Mon, 24 May 2021 13:43:44 +0300
Message-Id: <20210524104408.599645-4-tomi.valkeinen@ideasonboard.com>
In-Reply-To: <20210524104408.599645-1-tomi.valkeinen@ideasonboard.com>
References: <20210524104408.599645-1-tomi.valkeinen@ideasonboard.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

Series

v4l: subdev internal routing and streams | expand

Commit Message

Tomi Valkeinen May 24, 2021, 10:43 a.m. UTC

From: Sakari Ailus <sakari.ailus@linux.intel.com>

Instead of iterating over graph entities during the walk, iterate the pads
through which the entity was first reached. This is required in order to
make the entity pipeline pad-based rather than entity based.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 Documentation/driver-api/media/mc-core.rst    |  7 ++-
 drivers/media/mc/mc-entity.c                  | 51 +++++++++++--------
 drivers/media/platform/exynos4-is/media-dev.c | 20 ++++----
 drivers/media/platform/omap3isp/ispvideo.c    | 17 ++++---
 drivers/media/platform/vsp1/vsp1_video.c      | 12 ++---
 drivers/media/platform/xilinx/xilinx-dma.c    | 12 ++---
 drivers/media/v4l2-core/v4l2-mc.c             | 24 ++++-----
 drivers/staging/media/omap4iss/iss_video.c    | 36 ++++++-------
 include/media/media-entity.h                  |  7 +--
 9 files changed, 101 insertions(+), 85 deletions(-)

Comments

Jacopo Mondi July 8, 2021, 10:48 a.m. UTC | #1

Hi Tomi,

On Mon, May 24, 2021 at 01:43:44PM +0300, Tomi Valkeinen wrote:
> From: Sakari Ailus <sakari.ailus@linux.intel.com>

>

> Instead of iterating over graph entities during the walk, iterate the pads

> through which the entity was first reached. This is required in order to

> make the entity pipeline pad-based rather than entity based.

>

> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

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

> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

> ---

>  Documentation/driver-api/media/mc-core.rst    |  7 ++-

>  drivers/media/mc/mc-entity.c                  | 51 +++++++++++--------

>  drivers/media/platform/exynos4-is/media-dev.c | 20 ++++----

>  drivers/media/platform/omap3isp/ispvideo.c    | 17 ++++---

>  drivers/media/platform/vsp1/vsp1_video.c      | 12 ++---

>  drivers/media/platform/xilinx/xilinx-dma.c    | 12 ++---

>  drivers/media/v4l2-core/v4l2-mc.c             | 24 ++++-----

>  drivers/staging/media/omap4iss/iss_video.c    | 36 ++++++-------

>  include/media/media-entity.h                  |  7 +--

>  9 files changed, 101 insertions(+), 85 deletions(-)

>

> diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst

> index ba0aee982124..8a13640bed56 100644

> --- a/Documentation/driver-api/media/mc-core.rst

> +++ b/Documentation/driver-api/media/mc-core.rst

> @@ -169,8 +169,11 @@ Drivers initiate a graph traversal by calling

>  The graph structure, provided by the caller, is initialized to start graph

>  traversal at the given pad in an entity.

>

> -Drivers can then retrieve the next entity by calling

> -:c:func:`media_graph_walk_next()`

> +Drivers can then retrieve the next pad by calling

> +:c:func:`media_graph_walk_next()`. Only the pad through which the entity

> +is first reached is returned. If the caller is interested in knowing which

> +further pads would be connected, the :c:func:`media_entity_has_route()`


Not a big deal either, but this will be introduced later too

> +function can be used for that.

>

>  When the graph traversal is complete the function will return ``NULL``.

>

> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c

> index 0d58634b6fa8..32045671eaff 100644

> --- a/drivers/media/mc/mc-entity.c

> +++ b/drivers/media/mc/mc-entity.c

> @@ -341,9 +341,9 @@ static void media_graph_walk_iter(struct media_graph *graph)

>  	lockdep_assert_held(&next->graph_obj.mdev->graph_mutex);

>  }

>

> -struct media_entity *media_graph_walk_next(struct media_graph *graph)

> +struct media_pad *media_graph_walk_next(struct media_graph *graph)

>  {

> -	struct media_entity *entity;

> +	struct media_pad *pad;

>

>  	if (stack_top(graph) == NULL)

>  		return NULL;

> @@ -356,11 +356,11 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)

>  	while (link_top(graph) != &stack_top(graph)->entity->links)

>  		media_graph_walk_iter(graph);

>

> -	entity = stack_pop(graph)->entity;

> -	dev_dbg(entity->graph_obj.mdev->dev,

> -		"walk: returning entity '%s'\n", entity->name);

> +	pad = stack_pop(graph);

> +	dev_dbg(pad->graph_obj.mdev->dev,

> +		"walk: returning pad '%s':%u\n", pad->entity->name, pad->index);

>

> -	return entity;

> +	return pad;

>  }

>  EXPORT_SYMBOL_GPL(media_graph_walk_next);

>

> @@ -408,7 +408,8 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  {

>  	struct media_device *mdev = entity->graph_obj.mdev;

>  	struct media_graph *graph = &pipe->graph;

> -	struct media_entity *entity_err = entity;

> +	struct media_pad *pad = entity->pads;

> +	struct media_pad *pad_err = pad;

>  	struct media_link *link;

>  	int ret;

>

> @@ -418,9 +419,11 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  			goto error_graph_walk_start;

>  	}

>

> -	media_graph_walk_start(&pipe->graph, entity->pads);

> +	media_graph_walk_start(&pipe->graph, pad);

> +

> +	while ((pad = media_graph_walk_next(graph))) {

> +		struct media_entity *entity = pad->entity;

>

> -	while ((entity = media_graph_walk_next(graph))) {

>  		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);

>  		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);

>

> @@ -429,7 +432,7 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  		if (entity->pipe && entity->pipe != pipe) {

>  			pr_err("Pipe active for %s. Can't start for %s\n",

>  				entity->name,

> -				entity_err->name);

> +				pad_err->entity->name);

>  			ret = -EBUSY;

>  			goto error;

>  		}

> @@ -447,26 +450,27 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  		bitmap_fill(has_no_links, entity->num_pads);

>

>  		list_for_each_entry(link, &entity->links, list) {

> -			struct media_pad *pad = link->sink->entity == entity

> -						? link->sink : link->source;

> +			struct media_pad *other_pad =

> +				link->sink->entity == entity ?

> +				link->sink : link->source;

>

>  			/* Mark that a pad is connected by a link. */

> -			bitmap_clear(has_no_links, pad->index, 1);

> +			bitmap_clear(has_no_links, other_pad->index, 1);

>

>  			/*

>  			 * Pads that either do not need to connect or

>  			 * are connected through an enabled link are

>  			 * fine.

>  			 */

> -			if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||

> +			if (!(other_pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||

>  			    link->flags & MEDIA_LNK_FL_ENABLED)

> -				bitmap_set(active, pad->index, 1);

> +				bitmap_set(active, other_pad->index, 1);

>

>  			/*

>  			 * Link validation will only take place for

>  			 * sink ends of the link that are enabled.

>  			 */

> -			if (link->sink != pad ||

> +			if (link->sink != other_pad ||

>  			    !(link->flags & MEDIA_LNK_FL_ENABLED))

>  				continue;

>

> @@ -502,9 +506,11 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  	 * Link validation on graph failed. We revert what we did and

>  	 * return the error.

>  	 */

> -	media_graph_walk_start(graph, entity_err->pads);

> +	media_graph_walk_start(graph, pad_err);

> +

> +	while ((pad_err = media_graph_walk_next(graph))) {

> +		struct media_entity *entity_err = pad_err->entity;

>

> -	while ((entity_err = media_graph_walk_next(graph))) {

>  		/* Sanity check for negative stream_count */

>  		if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {

>  			entity_err->stream_count--;

> @@ -516,7 +522,7 @@ __must_check int __media_pipeline_start(struct media_entity *entity,

>  		 * We haven't increased stream_count further than this

>  		 * so we quit here.

>  		 */

> -		if (entity_err == entity)

> +		if (pad_err == pad)

>  			break;

>  	}

>

> @@ -543,8 +549,9 @@ EXPORT_SYMBOL_GPL(media_pipeline_start);

>

>  void __media_pipeline_stop(struct media_entity *entity)

>  {

> -	struct media_graph *graph = &entity->pipe->graph;

>  	struct media_pipeline *pipe = entity->pipe;

> +	struct media_graph *graph = &pipe->graph;

> +	struct media_pad *pad;

>

>  	/*

>  	 * If the following check fails, the driver has performed an

> @@ -555,7 +562,9 @@ void __media_pipeline_stop(struct media_entity *entity)

>

>  	media_graph_walk_start(graph, entity->pads);

>

> -	while ((entity = media_graph_walk_next(graph))) {

> +	while ((pad = media_graph_walk_next(graph))) {

> +		struct media_entity *entity = pad->entity;

> +

>  		/* Sanity check for negative stream_count */

>  		if (!WARN_ON_ONCE(entity->stream_count <= 0)) {

>  			entity->stream_count--;

> diff --git a/drivers/media/platform/exynos4-is/media-dev.c b/drivers/media/platform/exynos4-is/media-dev.c

> index 5aaecdf92c53..8938a6367703 100644

> --- a/drivers/media/platform/exynos4-is/media-dev.c

> +++ b/drivers/media/platform/exynos4-is/media-dev.c

> @@ -1164,7 +1164,7 @@ static int __fimc_md_modify_pipeline(struct media_entity *entity, bool enable)

>  static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,

>  				      struct media_graph *graph)

>  {

> -	struct media_entity *entity_err = entity;

> +	struct media_pad *pad, *pad_err = entity->pads;

>  	int ret;

>

>  	/*

> @@ -1173,13 +1173,13 @@ static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,

>  	 * through active links. This is needed as we cannot power on/off the

>  	 * subdevs in random order.

>  	 */

> -	media_graph_walk_start(graph, entity->pads);

> +	media_graph_walk_start(graph, pad_err);

>

> -	while ((entity = media_graph_walk_next(graph))) {

> -		if (!is_media_entity_v4l2_video_device(entity))

> +	while ((pad = media_graph_walk_next(graph))) {

> +		if (!is_media_entity_v4l2_video_device(pad->entity))

>  			continue;

>

> -		ret  = __fimc_md_modify_pipeline(entity, enable);

> +		ret  = __fimc_md_modify_pipeline(pad->entity, enable);

>

>  		if (ret < 0)

>  			goto err;

> @@ -1188,15 +1188,15 @@ static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,

>  	return 0;

>

>  err:

> -	media_graph_walk_start(graph, entity_err->pads);

> +	media_graph_walk_start(graph, pad_err);

>

> -	while ((entity_err = media_graph_walk_next(graph))) {

> -		if (!is_media_entity_v4l2_video_device(entity_err))

> +	while ((pad_err = media_graph_walk_next(graph))) {

> +		if (!is_media_entity_v4l2_video_device(pad_err->entity))

>  			continue;

>

> -		__fimc_md_modify_pipeline(entity_err, !enable);

> +		__fimc_md_modify_pipeline(pad_err->entity, !enable);

>

> -		if (entity_err == entity)

> +		if (pad_err == pad)

>  			break;

>  	}

>

> diff --git a/drivers/media/platform/omap3isp/ispvideo.c b/drivers/media/platform/omap3isp/ispvideo.c

> index 3c1485d59404..5c1cbb1a9003 100644

> --- a/drivers/media/platform/omap3isp/ispvideo.c

> +++ b/drivers/media/platform/omap3isp/ispvideo.c

> @@ -222,8 +222,8 @@ static int isp_video_get_graph_data(struct isp_video *video,

>  				    struct isp_pipeline *pipe)

>  {

>  	struct media_graph graph;

> -	struct media_entity *entity = &video->video.entity;

> -	struct media_device *mdev = entity->graph_obj.mdev;

> +	struct media_pad *pad = video->video.entity.pads;

> +	struct media_device *mdev = video->video.entity.graph_obj.mdev;

>  	struct isp_video *far_end = NULL;

>  	int ret;

>

> @@ -234,23 +234,24 @@ static int isp_video_get_graph_data(struct isp_video *video,

>  		return ret;

>  	}

>

> -	media_graph_walk_start(&graph, entity->pads);

> +	media_graph_walk_start(&graph, pad);

>

> -	while ((entity = media_graph_walk_next(&graph))) {

> +	while ((pad = media_graph_walk_next(&graph))) {

>  		struct isp_video *__video;

>

> -		media_entity_enum_set(&pipe->ent_enum, entity);

> +		media_entity_enum_set(&pipe->ent_enum, pad->entity);

>

>  		if (far_end != NULL)

>  			continue;

>

> -		if (entity == &video->video.entity)

> +		if (pad == video->video.entity.pads)

>  			continue;

>

> -		if (!is_media_entity_v4l2_video_device(entity))

> +		if (!is_media_entity_v4l2_video_device(pad->entity))

>  			continue;

>

> -		__video = to_isp_video(media_entity_to_video_device(entity));

> +		__video = to_isp_video(media_entity_to_video_device(

> +					       pad->entity));

>  		if (__video->type != video->type)

>  			far_end = __video;

>  	}

> diff --git a/drivers/media/platform/vsp1/vsp1_video.c b/drivers/media/platform/vsp1/vsp1_video.c

> index 61e4fbaba7b7..f2c36f2fdf53 100644

> --- a/drivers/media/platform/vsp1/vsp1_video.c

> +++ b/drivers/media/platform/vsp1/vsp1_video.c

> @@ -559,8 +559,8 @@ static int vsp1_video_pipeline_build(struct vsp1_pipeline *pipe,

>  				     struct vsp1_video *video)

>  {

>  	struct media_graph graph;

> -	struct media_entity *entity = &video->video.entity;

> -	struct media_device *mdev = entity->graph_obj.mdev;

> +	struct media_pad *pad = video->video.entity.pads;

> +	struct media_device *mdev = video->video.entity.graph_obj.mdev;

>  	unsigned int i;

>  	int ret;

>

> @@ -569,17 +569,17 @@ static int vsp1_video_pipeline_build(struct vsp1_pipeline *pipe,

>  	if (ret)

>  		return ret;

>

> -	media_graph_walk_start(&graph, entity->pads);

> +	media_graph_walk_start(&graph, pad);

>

> -	while ((entity = media_graph_walk_next(&graph))) {

> +	while ((pad = media_graph_walk_next(&graph))) {

>  		struct v4l2_subdev *subdev;

>  		struct vsp1_rwpf *rwpf;

>  		struct vsp1_entity *e;

>

> -		if (!is_media_entity_v4l2_subdev(entity))

> +		if (!is_media_entity_v4l2_subdev(pad->entity))

>  			continue;

>

> -		subdev = media_entity_to_v4l2_subdev(entity);

> +		subdev = media_entity_to_v4l2_subdev(pad->entity);

>  		e = to_vsp1_entity(subdev);

>  		list_add_tail(&e->list_pipe, &pipe->entities);

>  		e->pipe = pipe;

> diff --git a/drivers/media/platform/xilinx/xilinx-dma.c b/drivers/media/platform/xilinx/xilinx-dma.c

> index d64c3bee8b95..8df3c43aecbe 100644

> --- a/drivers/media/platform/xilinx/xilinx-dma.c

> +++ b/drivers/media/platform/xilinx/xilinx-dma.c

> @@ -175,8 +175,8 @@ static int xvip_pipeline_validate(struct xvip_pipeline *pipe,

>  				  struct xvip_dma *start)

>  {

>  	struct media_graph graph;

> -	struct media_entity *entity = &start->video.entity;

> -	struct media_device *mdev = entity->graph_obj.mdev;

> +	struct media_pad *pad = start->video.entity.pads;

> +	struct media_device *mdev = pad->entity->graph_obj.mdev;

>  	unsigned int num_inputs = 0;

>  	unsigned int num_outputs = 0;

>  	int ret;

> @@ -190,15 +190,15 @@ static int xvip_pipeline_validate(struct xvip_pipeline *pipe,

>  		return ret;

>  	}

>

> -	media_graph_walk_start(&graph, entity->pads);

> +	media_graph_walk_start(&graph, pad);

>

> -	while ((entity = media_graph_walk_next(&graph))) {

> +	while ((pad = media_graph_walk_next(&graph))) {

>  		struct xvip_dma *dma;

>

> -		if (entity->function != MEDIA_ENT_F_IO_V4L)

> +		if (pad->entity->function != MEDIA_ENT_F_IO_V4L)

>  			continue;

>

> -		dma = to_xvip_dma(media_entity_to_video_device(entity));

> +		dma = to_xvip_dma(media_entity_to_video_device(pad->entity));

>

>  		if (dma->pad.flags & MEDIA_PAD_FL_SINK) {

>  			pipe->output = dma;

> diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c

> index d215fe31b9a2..cbeb580c6754 100644

> --- a/drivers/media/v4l2-core/v4l2-mc.c

> +++ b/drivers/media/v4l2-core/v4l2-mc.c

> @@ -434,13 +434,14 @@ EXPORT_SYMBOL_GPL(v4l2_create_fwnode_links);

>  static int pipeline_pm_use_count(struct media_entity *entity,

>  	struct media_graph *graph)

>  {

> +	struct media_pad *pad;

>  	int use = 0;

>

>  	media_graph_walk_start(graph, entity->pads);

>

> -	while ((entity = media_graph_walk_next(graph))) {

> -		if (is_media_entity_v4l2_video_device(entity))

> -			use += entity->use_count;

> +	while ((pad = media_graph_walk_next(graph))) {

> +		if (is_media_entity_v4l2_video_device(pad->entity))

> +			use += pad->entity->use_count;

>  	}

>

>  	return use;

> @@ -493,7 +494,7 @@ static int pipeline_pm_power_one(struct media_entity *entity, int change)

>  static int pipeline_pm_power(struct media_entity *entity, int change,

>  	struct media_graph *graph)

>  {

> -	struct media_entity *first = entity;

> +	struct media_pad *tmp_pad, *pad;

>  	int ret = 0;

>

>  	if (!change)

> @@ -501,19 +502,18 @@ static int pipeline_pm_power(struct media_entity *entity, int change,

>

>  	media_graph_walk_start(graph, entity->pads);

>

> -	while (!ret && (entity = media_graph_walk_next(graph)))

> -		if (is_media_entity_v4l2_subdev(entity))

> -			ret = pipeline_pm_power_one(entity, change);

> +	while (!ret && (pad = media_graph_walk_next(graph)))

> +		if (is_media_entity_v4l2_subdev(pad->entity))

> +			ret = pipeline_pm_power_one(pad->entity, change);

>

>  	if (!ret)

>  		return ret;

>

> -	media_graph_walk_start(graph, first->pads);

> +	media_graph_walk_start(graph, entity->pads);

>

> -	while ((first = media_graph_walk_next(graph))

> -	       && first != entity)

> -		if (is_media_entity_v4l2_subdev(first))

> -			pipeline_pm_power_one(first, -change);

> +	while ((tmp_pad = media_graph_walk_next(graph)) && tmp_pad != pad)

> +		if (is_media_entity_v4l2_subdev(tmp_pad->entity))

> +			pipeline_pm_power_one(tmp_pad->entity, -change);

>

>  	return ret;

>  }

> diff --git a/drivers/staging/media/omap4iss/iss_video.c b/drivers/staging/media/omap4iss/iss_video.c

> index 760cd0ab1feb..8c25ad73a81e 100644

> --- a/drivers/staging/media/omap4iss/iss_video.c

> +++ b/drivers/staging/media/omap4iss/iss_video.c

> @@ -206,8 +206,8 @@ static struct iss_video *

>  iss_video_far_end(struct iss_video *video)

>  {

>  	struct media_graph graph;

> -	struct media_entity *entity = &video->video.entity;

> -	struct media_device *mdev = entity->graph_obj.mdev;

> +	struct media_pad *pad = video->video.entity.pads;

> +	struct media_device *mdev = video->video.entity.graph_obj.mdev;

>  	struct iss_video *far_end = NULL;

>

>  	mutex_lock(&mdev->graph_mutex);

> @@ -217,16 +217,17 @@ iss_video_far_end(struct iss_video *video)

>  		return NULL;

>  	}

>

> -	media_graph_walk_start(&graph, entity->pads);

> +	media_graph_walk_start(&graph, pad);

>

> -	while ((entity = media_graph_walk_next(&graph))) {

> -		if (entity == &video->video.entity)

> +	while ((pad = media_graph_walk_next(&graph))) {

> +		if (pad->entity == &video->video.entity)

>  			continue;

>

> -		if (!is_media_entity_v4l2_video_device(entity))

> +		if (!is_media_entity_v4l2_video_device(pad->entity))

>  			continue;

>

> -		far_end = to_iss_video(media_entity_to_video_device(entity));

> +		far_end = to_iss_video(media_entity_to_video_device(

> +						pad->entity));

>  		if (far_end->type != video->type)

>  			break;

>

> @@ -853,8 +854,8 @@ iss_video_streamon(struct file *file, void *fh, enum v4l2_buf_type type)

>  	struct iss_video_fh *vfh = to_iss_video_fh(fh);

>  	struct iss_video *video = video_drvdata(file);

>  	struct media_graph graph;

> -	struct media_entity *entity = &video->video.entity;

> -	struct media_device *mdev = entity->graph_obj.mdev;

> +	struct media_pad *pad = video->video.entity.pads;

> +	struct media_device *mdev = video->video.entity.graph_obj.mdev;

>  	enum iss_pipeline_state state;

>  	struct iss_pipeline *pipe;

>  	struct iss_video *far_end;

> @@ -870,31 +871,32 @@ iss_video_streamon(struct file *file, void *fh, enum v4l2_buf_type type)

>  	 * Start streaming on the pipeline. No link touching an entity in the

>  	 * pipeline can be activated or deactivated once streaming is started.

>  	 */

> -	pipe = entity->pipe

> -	     ? to_iss_pipeline(entity) : &video->pipe;

> +	pipe = pad->entity->pipe

> +	     ? to_iss_pipeline(pad->entity) : &video->pipe;

>  	pipe->external = NULL;

>  	pipe->external_rate = 0;

>  	pipe->external_bpp = 0;

>

> -	ret = media_entity_enum_init(&pipe->ent_enum, entity->graph_obj.mdev);

> +	ret = media_entity_enum_init(&pipe->ent_enum,

> +				     pad->entity->graph_obj.mdev);

>  	if (ret)

>  		goto err_graph_walk_init;

>

> -	ret = media_graph_walk_init(&graph, entity->graph_obj.mdev);

> +	ret = media_graph_walk_init(&graph, pad->entity->graph_obj.mdev);

>  	if (ret)

>  		goto err_graph_walk_init;

>

>  	if (video->iss->pdata->set_constraints)

>  		video->iss->pdata->set_constraints(video->iss, true);

>

> -	ret = media_pipeline_start(entity, &pipe->pipe);

> +	ret = media_pipeline_start(pad->entity, &pipe->pipe);

>  	if (ret < 0)

>  		goto err_media_pipeline_start;

>

>  	mutex_lock(&mdev->graph_mutex);

> -	media_graph_walk_start(&graph, entity->pads);

> -	while ((entity = media_graph_walk_next(&graph)))

> -		media_entity_enum_set(&pipe->ent_enum, entity);

> +	media_graph_walk_start(&graph, pad);

> +	while ((pad = media_graph_walk_next(&graph)))

> +		media_entity_enum_set(&pipe->ent_enum, pad->entity);

>  	mutex_unlock(&mdev->graph_mutex);

>

>  	/*

> diff --git a/include/media/media-entity.h b/include/media/media-entity.h

> index 5b55d6179e13..926fd201eae3 100644

> --- a/include/media/media-entity.h

> +++ b/include/media/media-entity.h

> @@ -926,10 +926,11 @@ void media_graph_walk_start(struct media_graph *graph, struct media_pad *pad);

>   * The graph structure must have been previously initialized with a call to

>   * media_graph_walk_start().

>   *

> - * Return: returns the next entity in the graph or %NULL if the whole graph

> - * have been traversed.

> + * Return: returns the next entity in the graph, identified by the pad through

> + * which it has been reached. If the whole graph has been traversed, return

> + * %NULL.

>   */

> -struct media_entity *media_graph_walk_next(struct media_graph *graph);

> +struct media_pad *media_graph_walk_next(struct media_graph *graph);

>

>  /**

>   * media_pipeline_start - Mark a pipeline as streaming

> --

> 2.25.1

>

diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst
index ba0aee982124..8a13640bed56 100644
--- a/Documentation/driver-api/media/mc-core.rst
+++ b/Documentation/driver-api/media/mc-core.rst
@@ -169,8 +169,11 @@  Drivers initiate a graph traversal by calling
 The graph structure, provided by the caller, is initialized to start graph
 traversal at the given pad in an entity.
 
-Drivers can then retrieve the next entity by calling
-:c:func:`media_graph_walk_next()`
+Drivers can then retrieve the next pad by calling
+:c:func:`media_graph_walk_next()`. Only the pad through which the entity
+is first reached is returned. If the caller is interested in knowing which
+further pads would be connected, the :c:func:`media_entity_has_route()`
+function can be used for that.
 
 When the graph traversal is complete the function will return ``NULL``.
 
diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 0d58634b6fa8..32045671eaff 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -341,9 +341,9 @@  static void media_graph_walk_iter(struct media_graph *graph)
 	lockdep_assert_held(&next->graph_obj.mdev->graph_mutex);
 }
 
-struct media_entity *media_graph_walk_next(struct media_graph *graph)
+struct media_pad *media_graph_walk_next(struct media_graph *graph)
 {
-	struct media_entity *entity;
+	struct media_pad *pad;
 
 	if (stack_top(graph) == NULL)
 		return NULL;
@@ -356,11 +356,11 @@  struct media_entity *media_graph_walk_next(struct media_graph *graph)
 	while (link_top(graph) != &stack_top(graph)->entity->links)
 		media_graph_walk_iter(graph);
 
-	entity = stack_pop(graph)->entity;
-	dev_dbg(entity->graph_obj.mdev->dev,
-		"walk: returning entity '%s'\n", entity->name);
+	pad = stack_pop(graph);
+	dev_dbg(pad->graph_obj.mdev->dev,
+		"walk: returning pad '%s':%u\n", pad->entity->name, pad->index);
 
-	return entity;
+	return pad;
 }
 EXPORT_SYMBOL_GPL(media_graph_walk_next);
 
@@ -408,7 +408,8 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 {
 	struct media_device *mdev = entity->graph_obj.mdev;
 	struct media_graph *graph = &pipe->graph;
-	struct media_entity *entity_err = entity;
+	struct media_pad *pad = entity->pads;
+	struct media_pad *pad_err = pad;
 	struct media_link *link;
 	int ret;
 
@@ -418,9 +419,11 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 			goto error_graph_walk_start;
 	}
 
-	media_graph_walk_start(&pipe->graph, entity->pads);
+	media_graph_walk_start(&pipe->graph, pad);
+
+	while ((pad = media_graph_walk_next(graph))) {
+		struct media_entity *entity = pad->entity;
 
-	while ((entity = media_graph_walk_next(graph))) {
 		DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
 		DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
 
@@ -429,7 +432,7 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 		if (entity->pipe && entity->pipe != pipe) {
 			pr_err("Pipe active for %s. Can't start for %s\n",
 				entity->name,
-				entity_err->name);
+				pad_err->entity->name);
 			ret = -EBUSY;
 			goto error;
 		}
@@ -447,26 +450,27 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 		bitmap_fill(has_no_links, entity->num_pads);
 
 		list_for_each_entry(link, &entity->links, list) {
-			struct media_pad *pad = link->sink->entity == entity
-						? link->sink : link->source;
+			struct media_pad *other_pad =
+				link->sink->entity == entity ?
+				link->sink : link->source;
 
 			/* Mark that a pad is connected by a link. */
-			bitmap_clear(has_no_links, pad->index, 1);
+			bitmap_clear(has_no_links, other_pad->index, 1);
 
 			/*
 			 * Pads that either do not need to connect or
 			 * are connected through an enabled link are
 			 * fine.
 			 */
-			if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
+			if (!(other_pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
 			    link->flags & MEDIA_LNK_FL_ENABLED)
-				bitmap_set(active, pad->index, 1);
+				bitmap_set(active, other_pad->index, 1);
 
 			/*
 			 * Link validation will only take place for
 			 * sink ends of the link that are enabled.
 			 */
-			if (link->sink != pad ||
+			if (link->sink != other_pad ||
 			    !(link->flags & MEDIA_LNK_FL_ENABLED))
 				continue;
 
@@ -502,9 +506,11 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 	 * Link validation on graph failed. We revert what we did and
 	 * return the error.
 	 */
-	media_graph_walk_start(graph, entity_err->pads);
+	media_graph_walk_start(graph, pad_err);
+
+	while ((pad_err = media_graph_walk_next(graph))) {
+		struct media_entity *entity_err = pad_err->entity;
 
-	while ((entity_err = media_graph_walk_next(graph))) {
 		/* Sanity check for negative stream_count */
 		if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) {
 			entity_err->stream_count--;
@@ -516,7 +522,7 @@  __must_check int __media_pipeline_start(struct media_entity *entity,
 		 * We haven't increased stream_count further than this
 		 * so we quit here.
 		 */
-		if (entity_err == entity)
+		if (pad_err == pad)
 			break;
 	}
 
@@ -543,8 +549,9 @@  EXPORT_SYMBOL_GPL(media_pipeline_start);
 
 void __media_pipeline_stop(struct media_entity *entity)
 {
-	struct media_graph *graph = &entity->pipe->graph;
 	struct media_pipeline *pipe = entity->pipe;
+	struct media_graph *graph = &pipe->graph;
+	struct media_pad *pad;
 
 	/*
 	 * If the following check fails, the driver has performed an
@@ -555,7 +562,9 @@  void __media_pipeline_stop(struct media_entity *entity)
 
 	media_graph_walk_start(graph, entity->pads);
 
-	while ((entity = media_graph_walk_next(graph))) {
+	while ((pad = media_graph_walk_next(graph))) {
+		struct media_entity *entity = pad->entity;
+
 		/* Sanity check for negative stream_count */
 		if (!WARN_ON_ONCE(entity->stream_count <= 0)) {
 			entity->stream_count--;
diff --git a/drivers/media/platform/exynos4-is/media-dev.c b/drivers/media/platform/exynos4-is/media-dev.c
index 5aaecdf92c53..8938a6367703 100644
--- a/drivers/media/platform/exynos4-is/media-dev.c
+++ b/drivers/media/platform/exynos4-is/media-dev.c
@@ -1164,7 +1164,7 @@  static int __fimc_md_modify_pipeline(struct media_entity *entity, bool enable)
 static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,
 				      struct media_graph *graph)
 {
-	struct media_entity *entity_err = entity;
+	struct media_pad *pad, *pad_err = entity->pads;
 	int ret;
 
 	/*
@@ -1173,13 +1173,13 @@  static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,
 	 * through active links. This is needed as we cannot power on/off the
 	 * subdevs in random order.
 	 */
-	media_graph_walk_start(graph, entity->pads);
+	media_graph_walk_start(graph, pad_err);
 
-	while ((entity = media_graph_walk_next(graph))) {
-		if (!is_media_entity_v4l2_video_device(entity))
+	while ((pad = media_graph_walk_next(graph))) {
+		if (!is_media_entity_v4l2_video_device(pad->entity))
 			continue;
 
-		ret  = __fimc_md_modify_pipeline(entity, enable);
+		ret  = __fimc_md_modify_pipeline(pad->entity, enable);
 
 		if (ret < 0)
 			goto err;
@@ -1188,15 +1188,15 @@  static int __fimc_md_modify_pipelines(struct media_entity *entity, bool enable,
 	return 0;
 
 err:
-	media_graph_walk_start(graph, entity_err->pads);
+	media_graph_walk_start(graph, pad_err);
 
-	while ((entity_err = media_graph_walk_next(graph))) {
-		if (!is_media_entity_v4l2_video_device(entity_err))
+	while ((pad_err = media_graph_walk_next(graph))) {
+		if (!is_media_entity_v4l2_video_device(pad_err->entity))
 			continue;
 
-		__fimc_md_modify_pipeline(entity_err, !enable);
+		__fimc_md_modify_pipeline(pad_err->entity, !enable);
 
-		if (entity_err == entity)
+		if (pad_err == pad)
 			break;
 	}
 
diff --git a/drivers/media/platform/omap3isp/ispvideo.c b/drivers/media/platform/omap3isp/ispvideo.c
index 3c1485d59404..5c1cbb1a9003 100644
--- a/drivers/media/platform/omap3isp/ispvideo.c
+++ b/drivers/media/platform/omap3isp/ispvideo.c
@@ -222,8 +222,8 @@  static int isp_video_get_graph_data(struct isp_video *video,
 				    struct isp_pipeline *pipe)
 {
 	struct media_graph graph;
-	struct media_entity *entity = &video->video.entity;
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_pad *pad = video->video.entity.pads;
+	struct media_device *mdev = video->video.entity.graph_obj.mdev;
 	struct isp_video *far_end = NULL;
 	int ret;
 
@@ -234,23 +234,24 @@  static int isp_video_get_graph_data(struct isp_video *video,
 		return ret;
 	}
 
-	media_graph_walk_start(&graph, entity->pads);
+	media_graph_walk_start(&graph, pad);
 
-	while ((entity = media_graph_walk_next(&graph))) {
+	while ((pad = media_graph_walk_next(&graph))) {
 		struct isp_video *__video;
 
-		media_entity_enum_set(&pipe->ent_enum, entity);
+		media_entity_enum_set(&pipe->ent_enum, pad->entity);
 
 		if (far_end != NULL)
 			continue;
 
-		if (entity == &video->video.entity)
+		if (pad == video->video.entity.pads)
 			continue;
 
-		if (!is_media_entity_v4l2_video_device(entity))
+		if (!is_media_entity_v4l2_video_device(pad->entity))
 			continue;
 
-		__video = to_isp_video(media_entity_to_video_device(entity));
+		__video = to_isp_video(media_entity_to_video_device(
+					       pad->entity));
 		if (__video->type != video->type)
 			far_end = __video;
 	}
diff --git a/drivers/media/platform/vsp1/vsp1_video.c b/drivers/media/platform/vsp1/vsp1_video.c
index 61e4fbaba7b7..f2c36f2fdf53 100644
--- a/drivers/media/platform/vsp1/vsp1_video.c
+++ b/drivers/media/platform/vsp1/vsp1_video.c
@@ -559,8 +559,8 @@  static int vsp1_video_pipeline_build(struct vsp1_pipeline *pipe,
 				     struct vsp1_video *video)
 {
 	struct media_graph graph;
-	struct media_entity *entity = &video->video.entity;
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_pad *pad = video->video.entity.pads;
+	struct media_device *mdev = video->video.entity.graph_obj.mdev;
 	unsigned int i;
 	int ret;
 
@@ -569,17 +569,17 @@  static int vsp1_video_pipeline_build(struct vsp1_pipeline *pipe,
 	if (ret)
 		return ret;
 
-	media_graph_walk_start(&graph, entity->pads);
+	media_graph_walk_start(&graph, pad);
 
-	while ((entity = media_graph_walk_next(&graph))) {
+	while ((pad = media_graph_walk_next(&graph))) {
 		struct v4l2_subdev *subdev;
 		struct vsp1_rwpf *rwpf;
 		struct vsp1_entity *e;
 
-		if (!is_media_entity_v4l2_subdev(entity))
+		if (!is_media_entity_v4l2_subdev(pad->entity))
 			continue;
 
-		subdev = media_entity_to_v4l2_subdev(entity);
+		subdev = media_entity_to_v4l2_subdev(pad->entity);
 		e = to_vsp1_entity(subdev);
 		list_add_tail(&e->list_pipe, &pipe->entities);
 		e->pipe = pipe;
diff --git a/drivers/media/platform/xilinx/xilinx-dma.c b/drivers/media/platform/xilinx/xilinx-dma.c
index d64c3bee8b95..8df3c43aecbe 100644
--- a/drivers/media/platform/xilinx/xilinx-dma.c
+++ b/drivers/media/platform/xilinx/xilinx-dma.c
@@ -175,8 +175,8 @@  static int xvip_pipeline_validate(struct xvip_pipeline *pipe,
 				  struct xvip_dma *start)
 {
 	struct media_graph graph;
-	struct media_entity *entity = &start->video.entity;
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_pad *pad = start->video.entity.pads;
+	struct media_device *mdev = pad->entity->graph_obj.mdev;
 	unsigned int num_inputs = 0;
 	unsigned int num_outputs = 0;
 	int ret;
@@ -190,15 +190,15 @@  static int xvip_pipeline_validate(struct xvip_pipeline *pipe,
 		return ret;
 	}
 
-	media_graph_walk_start(&graph, entity->pads);
+	media_graph_walk_start(&graph, pad);
 
-	while ((entity = media_graph_walk_next(&graph))) {
+	while ((pad = media_graph_walk_next(&graph))) {
 		struct xvip_dma *dma;
 
-		if (entity->function != MEDIA_ENT_F_IO_V4L)
+		if (pad->entity->function != MEDIA_ENT_F_IO_V4L)
 			continue;
 
-		dma = to_xvip_dma(media_entity_to_video_device(entity));
+		dma = to_xvip_dma(media_entity_to_video_device(pad->entity));
 
 		if (dma->pad.flags & MEDIA_PAD_FL_SINK) {
 			pipe->output = dma;
diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
index d215fe31b9a2..cbeb580c6754 100644
--- a/drivers/media/v4l2-core/v4l2-mc.c
+++ b/drivers/media/v4l2-core/v4l2-mc.c
@@ -434,13 +434,14 @@  EXPORT_SYMBOL_GPL(v4l2_create_fwnode_links);
 static int pipeline_pm_use_count(struct media_entity *entity,
 	struct media_graph *graph)
 {
+	struct media_pad *pad;
 	int use = 0;
 
 	media_graph_walk_start(graph, entity->pads);
 
-	while ((entity = media_graph_walk_next(graph))) {
-		if (is_media_entity_v4l2_video_device(entity))
-			use += entity->use_count;
+	while ((pad = media_graph_walk_next(graph))) {
+		if (is_media_entity_v4l2_video_device(pad->entity))
+			use += pad->entity->use_count;
 	}
 
 	return use;
@@ -493,7 +494,7 @@  static int pipeline_pm_power_one(struct media_entity *entity, int change)
 static int pipeline_pm_power(struct media_entity *entity, int change,
 	struct media_graph *graph)
 {
-	struct media_entity *first = entity;
+	struct media_pad *tmp_pad, *pad;
 	int ret = 0;
 
 	if (!change)
@@ -501,19 +502,18 @@  static int pipeline_pm_power(struct media_entity *entity, int change,
 
 	media_graph_walk_start(graph, entity->pads);
 
-	while (!ret && (entity = media_graph_walk_next(graph)))
-		if (is_media_entity_v4l2_subdev(entity))
-			ret = pipeline_pm_power_one(entity, change);
+	while (!ret && (pad = media_graph_walk_next(graph)))
+		if (is_media_entity_v4l2_subdev(pad->entity))
+			ret = pipeline_pm_power_one(pad->entity, change);
 
 	if (!ret)
 		return ret;
 
-	media_graph_walk_start(graph, first->pads);
+	media_graph_walk_start(graph, entity->pads);
 
-	while ((first = media_graph_walk_next(graph))
-	       && first != entity)
-		if (is_media_entity_v4l2_subdev(first))
-			pipeline_pm_power_one(first, -change);
+	while ((tmp_pad = media_graph_walk_next(graph)) && tmp_pad != pad)
+		if (is_media_entity_v4l2_subdev(tmp_pad->entity))
+			pipeline_pm_power_one(tmp_pad->entity, -change);
 
 	return ret;
 }
diff --git a/drivers/staging/media/omap4iss/iss_video.c b/drivers/staging/media/omap4iss/iss_video.c
index 760cd0ab1feb..8c25ad73a81e 100644
--- a/drivers/staging/media/omap4iss/iss_video.c
+++ b/drivers/staging/media/omap4iss/iss_video.c
@@ -206,8 +206,8 @@  static struct iss_video *
 iss_video_far_end(struct iss_video *video)
 {
 	struct media_graph graph;
-	struct media_entity *entity = &video->video.entity;
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_pad *pad = video->video.entity.pads;
+	struct media_device *mdev = video->video.entity.graph_obj.mdev;
 	struct iss_video *far_end = NULL;
 
 	mutex_lock(&mdev->graph_mutex);
@@ -217,16 +217,17 @@  iss_video_far_end(struct iss_video *video)
 		return NULL;
 	}
 
-	media_graph_walk_start(&graph, entity->pads);
+	media_graph_walk_start(&graph, pad);
 
-	while ((entity = media_graph_walk_next(&graph))) {
-		if (entity == &video->video.entity)
+	while ((pad = media_graph_walk_next(&graph))) {
+		if (pad->entity == &video->video.entity)
 			continue;
 
-		if (!is_media_entity_v4l2_video_device(entity))
+		if (!is_media_entity_v4l2_video_device(pad->entity))
 			continue;
 
-		far_end = to_iss_video(media_entity_to_video_device(entity));
+		far_end = to_iss_video(media_entity_to_video_device(
+						pad->entity));
 		if (far_end->type != video->type)
 			break;
 
@@ -853,8 +854,8 @@  iss_video_streamon(struct file *file, void *fh, enum v4l2_buf_type type)
 	struct iss_video_fh *vfh = to_iss_video_fh(fh);
 	struct iss_video *video = video_drvdata(file);
 	struct media_graph graph;
-	struct media_entity *entity = &video->video.entity;
-	struct media_device *mdev = entity->graph_obj.mdev;
+	struct media_pad *pad = video->video.entity.pads;
+	struct media_device *mdev = video->video.entity.graph_obj.mdev;
 	enum iss_pipeline_state state;
 	struct iss_pipeline *pipe;
 	struct iss_video *far_end;
@@ -870,31 +871,32 @@  iss_video_streamon(struct file *file, void *fh, enum v4l2_buf_type type)
 	 * Start streaming on the pipeline. No link touching an entity in the
 	 * pipeline can be activated or deactivated once streaming is started.
 	 */
-	pipe = entity->pipe
-	     ? to_iss_pipeline(entity) : &video->pipe;
+	pipe = pad->entity->pipe
+	     ? to_iss_pipeline(pad->entity) : &video->pipe;
 	pipe->external = NULL;
 	pipe->external_rate = 0;
 	pipe->external_bpp = 0;
 
-	ret = media_entity_enum_init(&pipe->ent_enum, entity->graph_obj.mdev);
+	ret = media_entity_enum_init(&pipe->ent_enum,
+				     pad->entity->graph_obj.mdev);
 	if (ret)
 		goto err_graph_walk_init;
 
-	ret = media_graph_walk_init(&graph, entity->graph_obj.mdev);
+	ret = media_graph_walk_init(&graph, pad->entity->graph_obj.mdev);
 	if (ret)
 		goto err_graph_walk_init;
 
 	if (video->iss->pdata->set_constraints)
 		video->iss->pdata->set_constraints(video->iss, true);
 
-	ret = media_pipeline_start(entity, &pipe->pipe);
+	ret = media_pipeline_start(pad->entity, &pipe->pipe);
 	if (ret < 0)
 		goto err_media_pipeline_start;
 
 	mutex_lock(&mdev->graph_mutex);
-	media_graph_walk_start(&graph, entity->pads);
-	while ((entity = media_graph_walk_next(&graph)))
-		media_entity_enum_set(&pipe->ent_enum, entity);
+	media_graph_walk_start(&graph, pad);
+	while ((pad = media_graph_walk_next(&graph)))
+		media_entity_enum_set(&pipe->ent_enum, pad->entity);
 	mutex_unlock(&mdev->graph_mutex);
 
 	/*
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index 5b55d6179e13..926fd201eae3 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -926,10 +926,11 @@  void media_graph_walk_start(struct media_graph *graph, struct media_pad *pad);
  * The graph structure must have been previously initialized with a call to
  * media_graph_walk_start().
  *
- * Return: returns the next entity in the graph or %NULL if the whole graph
- * have been traversed.
+ * Return: returns the next entity in the graph, identified by the pad through
+ * which it has been reached. If the whole graph has been traversed, return
+ * %NULL.
  */
-struct media_entity *media_graph_walk_next(struct media_graph *graph);
+struct media_pad *media_graph_walk_next(struct media_graph *graph);
 
 /**
  * media_pipeline_start - Mark a pipeline as streaming

[v7,03/27] media: entity: Walk the graph based on pads

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