[media] v4l: Add generic pipeline power management code (76413791) · Commits · 戴 / test

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

+182 −1

Original line number	Diff line number	Diff line
		@@ -3,6 +3,8 @@
		*
		* Copyright (c) 2016 Mauro Carvalho Chehab <mchehab@osg.samsung.com>
		* Copyright (C) 2016 Shuah Khan <shuahkh@osg.samsung.com>
		* Copyright (C) 2006-2010 Nokia Corporation
		* Copyright (c) 2016 Intel Corporation.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		@@ -16,10 +18,15 @@
		*/

		#include <linux/module.h>
		#include <media/media-entity.h>
		#include <linux/pci.h>
		#include <linux/usb.h>
		#include <media/media-device.h>
		#include <media/media-entity.h>
		#include <media/v4l2-fh.h>
		#include <media/v4l2-mc.h>
		#include <media/v4l2-subdev.h>
		#include <media/media-device.h>
		#include <media/v4l2-mc.h>
		#include <media/videobuf2-core.h>

		int v4l2_mc_create_media_graph(struct media_device *mdev)
		@@ -236,3 +243,177 @@ int v4l_vb2q_enable_media_source(struct vb2_queue *q)
		return v4l_enable_media_source(fh->vdev);
		}
		EXPORT_SYMBOL_GPL(v4l_vb2q_enable_media_source);

		/* -----------------------------------------------------------------------------
		* Pipeline power management
		*
		* Entities must be powered up when part of a pipeline that contains at least
		* one open video device node.
		*
		* To achieve this use the entity use_count field to track the number of users.
		* For entities corresponding to video device nodes the use_count field stores
		* the users count of the node. For entities corresponding to subdevs the
		* use_count field stores the total number of users of all video device nodes
		* in the pipeline.
		*
		* The v4l2_pipeline_pm_use() function must be called in the open() and
		* close() handlers of video device nodes. It increments or decrements the use
		* count of all subdev entities in the pipeline.
		*
		* To react to link management on powered pipelines, the link setup notification
		* callback updates the use count of all entities in the source and sink sides
		* of the link.
		*/

		/*
		* pipeline_pm_use_count - Count the number of users of a pipeline
		* @entity: The entity
		*
		* Return the total number of users of all video device nodes in the pipeline.
		*/
		static int pipeline_pm_use_count(struct media_entity *entity,
		struct media_entity_graph *graph)
		{
		int use = 0;

		media_entity_graph_walk_start(graph, entity);

		while ((entity = media_entity_graph_walk_next(graph))) {
		if (is_media_entity_v4l2_io(entity))
		use += entity->use_count;
		}

		return use;
		}

		/*
		* pipeline_pm_power_one - Apply power change to an entity
		* @entity: The entity
		* @change: Use count change
		*
		* Change the entity use count by @change. If the entity is a subdev update its
		* power state by calling the core::s_power operation when the use count goes
		* from 0 to != 0 or from != 0 to 0.
		*
		* Return 0 on success or a negative error code on failure.
		*/
		static int pipeline_pm_power_one(struct media_entity *entity, int change)
		{
		struct v4l2_subdev *subdev;
		int ret;

		subdev = is_media_entity_v4l2_subdev(entity)
		? media_entity_to_v4l2_subdev(entity) : NULL;

		if (entity->use_count == 0 && change > 0 && subdev != NULL) {
		ret = v4l2_subdev_call(subdev, core, s_power, 1);
		if (ret < 0 && ret != -ENOIOCTLCMD)
		return ret;
		}

		entity->use_count += change;
		WARN_ON(entity->use_count < 0);

		if (entity->use_count == 0 && change < 0 && subdev != NULL)
		v4l2_subdev_call(subdev, core, s_power, 0);

		return 0;
		}

		/*
		* pipeline_pm_power - Apply power change to all entities in a pipeline
		* @entity: The entity
		* @change: Use count change
		*
		* Walk the pipeline to update the use count and the power state of all non-node
		* entities.
		*
		* Return 0 on success or a negative error code on failure.
		*/
		static int pipeline_pm_power(struct media_entity *entity, int change,
		struct media_entity_graph *graph)
		{
		struct media_entity *first = entity;
		int ret = 0;

		if (!change)
		return 0;

		media_entity_graph_walk_start(graph, entity);

		while (!ret && (entity = media_entity_graph_walk_next(graph)))
		if (is_media_entity_v4l2_subdev(entity))
		ret = pipeline_pm_power_one(entity, change);

		if (!ret)
		return ret;

		media_entity_graph_walk_start(graph, first);

		while ((first = media_entity_graph_walk_next(graph))
		&& first != entity)
		if (is_media_entity_v4l2_subdev(first))
		pipeline_pm_power_one(first, -change);

		return ret;
		}

		int v4l2_pipeline_pm_use(struct media_entity *entity, int use)
		{
		struct media_device *mdev = entity->graph_obj.mdev;
		int change = use ? 1 : -1;
		int ret;

		mutex_lock(&mdev->graph_mutex);

		/* Apply use count to node. */
		entity->use_count += change;
		WARN_ON(entity->use_count < 0);

		/* Apply power change to connected non-nodes. */
		ret = pipeline_pm_power(entity, change, &mdev->pm_count_walk);
		if (ret < 0)
		entity->use_count -= change;

		mutex_unlock(&mdev->graph_mutex);

		return ret;
		}
		EXPORT_SYMBOL_GPL(v4l2_pipeline_pm_use);

		int v4l2_pipeline_link_notify(struct media_link *link, u32 flags,
		unsigned int notification)
		{
		struct media_entity_graph *graph = &link->graph_obj.mdev->pm_count_walk;
		struct media_entity *source = link->source->entity;
		struct media_entity *sink = link->sink->entity;
		int source_use;
		int sink_use;
		int ret = 0;

		source_use = pipeline_pm_use_count(source, graph);
		sink_use = pipeline_pm_use_count(sink, graph);

		if (notification == MEDIA_DEV_NOTIFY_POST_LINK_CH &&
		!(flags & MEDIA_LNK_FL_ENABLED)) {
		/* Powering off entities is assumed to never fail. */
		pipeline_pm_power(source, -sink_use, graph);
		pipeline_pm_power(sink, -source_use, graph);
		return 0;
		}

		if (notification == MEDIA_DEV_NOTIFY_PRE_LINK_CH &&
		(flags & MEDIA_LNK_FL_ENABLED)) {

		ret = pipeline_pm_power(source, sink_use, graph);
		if (ret < 0)
		return ret;

		ret = pipeline_pm_power(sink, source_use, graph);
		if (ret < 0)
		pipeline_pm_power(source, -sink_use, graph);
		}

		return ret;
		}
		EXPORT_SYMBOL_GPL(v4l2_pipeline_link_notify);

include/media/v4l2-mc.h

+42 −1

Original line number	Diff line number	Diff line
		@@ -2,6 +2,8 @@
		* v4l2-mc.h - Media Controller V4L2 types and prototypes
		*
		* Copyright (C) 2016 Mauro Carvalho Chehab <mchehab@osg.samsung.com>
		* Copyright (C) 2006-2010 Nokia Corporation
		* Copyright (c) 2016 Intel Corporation.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		@@ -19,6 +21,7 @@

		#include <media/media-device.h>
		#include <media/v4l2-dev.h>
		#include <linux/types.h>

		/**
		* enum tuner_pad_index - tuner pad index for MEDIA_ENT_F_TUNER
		@@ -165,6 +168,45 @@ void v4l_disable_media_source(struct video_device *vdev);
		*/
		int v4l_vb2q_enable_media_source(struct vb2_queue *q);


		/**
		* v4l2_pipeline_pm_use - Update the use count of an entity
		* @entity: The entity
		* @use: Use (1) or stop using (0) the entity
		*
		* Update the use count of all entities in the pipeline and power entities on or
		* off accordingly.
		*
		* This function is intended to be called in video node open (use ==
		* 1) and release (use == 0). It uses struct media_entity.use_count to
		* track the power status. The use of this function should be paired
		* with v4l2_pipeline_link_notify().
		*
		* Return 0 on success or a negative error code on failure. Powering entities
		* off is assumed to never fail. No failure can occur when the use parameter is
		* set to 0.
		*/
		int v4l2_pipeline_pm_use(struct media_entity *entity, int use);


		/**
		* v4l2_pipeline_link_notify - Link management notification callback
		* @link: The link
		* @flags: New link flags that will be applied
		* @notification: The link's state change notification type (MEDIA_DEV_NOTIFY_*)
		*
		* React to link management on powered pipelines by updating the use count of
		* all entities in the source and sink sides of the link. Entities are powered
		* on or off accordingly. The use of this function should be paired
		* with v4l2_pipeline_pm_use().
		*
		* Return 0 on success or a negative error code on failure. Powering entities
		* off is assumed to never fail. This function will not fail for disconnection
		* events.
		*/
		int v4l2_pipeline_link_notify(struct media_link *link, u32 flags,
		unsigned int notification);

		#else

		static inline int v4l2_mc_create_media_graph(struct media_device *mdev)
		@@ -186,6 +228,5 @@ static int v4l_vb2q_enable_media_source(struct vb2_queue *q)
		{
		return 0;
		}

		#endif
		#endif /* _V4L2_MC_H */

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