@@ -2,6 +2,8 @@
* Media Controller ancillary functions
*
* (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
@@ -17,9 +19,10 @@
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/usb.h>
+#include <media/media-device.h>
#include <media/media-entity.h>
#include <media/v4l2-mc.h>
-
+#include <media/v4l2-subdev.h>
struct media_device *v4l2_mc_pci_media_device_init(struct pci_dev *pci_dev,
const char *name)
@@ -256,3 +259,177 @@ int v4l2_mc_create_media_graph(struct media_device *mdev)
return 0;
}
EXPORT_SYMBOL_GPL(v4l2_mc_create_media_graph);
+
+/* -----------------------------------------------------------------------------
+ * 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);
@@ -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
@@ -18,6 +20,7 @@
#define _V4L2_MC_H
#include <media/media-device.h>
+#include <linux/types.h>
/**
* enum tuner_pad_index - tuner pad index for MEDIA_ENT_F_TUNER
@@ -169,4 +172,43 @@ struct media_device *__v4l2_mc_usb_media_device_init(struct usb_device *udev,
#define v4l2_mc_usb_media_device_init(udev, name) \
__v4l2_mc_usb_media_device_init(udev, name, KBUILD_MODNAME)
+/**
+ * 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);
+
+
#endif