[RFCv12 PATCH 03/29] media-request: implement media requests

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From: Hans Verkuil <hans.verkuil@xxxxxxxxx>

Add initial media request support.

Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
 drivers/media/Makefile        |   3 +-
 drivers/media/media-device.c  |  13 ++
 drivers/media/media-request.c | 418 ++++++++++++++++++++++++++++++++++
 include/media/media-device.h  |  17 ++
 include/media/media-request.h | 193 ++++++++++++++++
 5 files changed, 643 insertions(+), 1 deletion(-)
 create mode 100644 drivers/media/media-request.c
 create mode 100644 include/media/media-request.h

diff --git a/drivers/media/Makefile b/drivers/media/Makefile
index 594b462ddf0e..985d35ec6b29 100644
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -3,7 +3,8 @@
 # Makefile for the kernel multimedia device drivers.
 #
 
-media-objs	:= media-device.o media-devnode.o media-entity.o
+media-objs	:= media-device.o media-devnode.o media-entity.o \
+		   media-request.o
 
 #
 # I2C drivers should come before other drivers, otherwise they'll fail
diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 35e81f7c0d2f..25d7e2a3ee84 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -32,6 +32,7 @@
 #include <media/media-device.h>
 #include <media/media-devnode.h>
 #include <media/media-entity.h>
+#include <media/media-request.h>
 
 #ifdef CONFIG_MEDIA_CONTROLLER
 
@@ -366,6 +367,15 @@ static long media_device_get_topology(struct media_device *mdev,
 	return ret;
 }
 
+static long media_device_request_alloc(struct media_device *mdev,
+				       struct media_request_alloc *alloc)
+{
+	if (!mdev->ops || !mdev->ops->req_validate || !mdev->ops->req_queue)
+		return -ENOTTY;
+
+	return media_request_alloc(mdev, alloc);
+}
+
 static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd)
 {
 	/* All media IOCTLs are _IOWR() */
@@ -414,6 +424,7 @@ static const struct media_ioctl_info ioctl_info[] = {
 	MEDIA_IOC(ENUM_LINKS, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX),
 	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),
 	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(REQUEST_ALLOC, media_device_request_alloc, 0),
 };
 
 static long media_device_ioctl(struct file *filp, unsigned int cmd,
@@ -686,6 +697,8 @@ void media_device_init(struct media_device *mdev)
 	INIT_LIST_HEAD(&mdev->pads);
 	INIT_LIST_HEAD(&mdev->links);
 	INIT_LIST_HEAD(&mdev->entity_notify);
+
+	mutex_init(&mdev->req_queue_mutex);
 	mutex_init(&mdev->graph_mutex);
 	ida_init(&mdev->entity_internal_idx);
 
diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
new file mode 100644
index 000000000000..22881d5700c8
--- /dev/null
+++ b/drivers/media/media-request.c
@@ -0,0 +1,418 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Media device request objects
+ *
+ * Copyright (C) 2018 Intel Corporation
+ * Copyright (C) 2018 Google, Inc.
+ *
+ * Author: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
+ */
+
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
+
+#include <media/media-device.h>
+#include <media/media-request.h>
+
+static const char * const request_state[] = {
+	[MEDIA_REQUEST_STATE_IDLE]	 = "idle",
+	[MEDIA_REQUEST_STATE_VALIDATING] = "validating",
+	[MEDIA_REQUEST_STATE_QUEUED]	 = "queued",
+	[MEDIA_REQUEST_STATE_COMPLETE]	 = "complete",
+	[MEDIA_REQUEST_STATE_CLEANING]	 = "cleaning",
+};
+
+static const char *
+media_request_state_str(enum media_request_state state)
+{
+	if (WARN_ON(state >= ARRAY_SIZE(request_state)))
+		return "unknown";
+	return request_state[state];
+}
+
+static void media_request_clean(struct media_request *req)
+{
+	struct media_request_object *obj, *obj_safe;
+
+	WARN_ON(atomic_read(&req->state) != MEDIA_REQUEST_STATE_CLEANING);
+
+	list_for_each_entry_safe(obj, obj_safe, &req->objects, list) {
+		media_request_object_unbind(obj);
+		media_request_object_put(obj);
+	}
+
+	req->num_incomplete_objects = 0;
+	wake_up_interruptible_all(&req->poll_wait);
+}
+
+static void media_request_release(struct kref *kref)
+{
+	struct media_request *req =
+		container_of(kref, struct media_request, kref);
+	struct media_device *mdev = req->mdev;
+
+	dev_dbg(mdev->dev, "request: release %s\n", req->debug_str);
+
+	atomic_set(&req->state, MEDIA_REQUEST_STATE_CLEANING);
+
+	media_request_clean(req);
+
+	if (mdev->ops->req_free)
+		mdev->ops->req_free(req);
+	else
+		kfree(req);
+}
+
+void media_request_put(struct media_request *req)
+{
+	kref_put(&req->kref, media_request_release);
+}
+EXPORT_SYMBOL_GPL(media_request_put);
+
+void media_request_cancel(struct media_request *req)
+{
+	struct media_request_object *obj, *obj_safe;
+
+	/*
+	 * This is serialized with the req_queue_mutex and streaming
+	 * has stopped, so there is no need to take the spinlock here.
+	 */
+	WARN_ON_ONCE(!mutex_is_locked(&req->mdev->req_queue_mutex));
+	if (atomic_read(&req->state) != MEDIA_REQUEST_STATE_QUEUED)
+		return;
+
+	list_for_each_entry_safe(obj, obj_safe, &req->objects, list)
+		if (obj->ops->cancel)
+			obj->ops->cancel(obj);
+}
+EXPORT_SYMBOL_GPL(media_request_cancel);
+
+static int media_request_close(struct inode *inode, struct file *filp)
+{
+	struct media_request *req = filp->private_data;
+
+	media_request_put(req);
+	return 0;
+}
+
+static unsigned int media_request_poll(struct file *filp,
+				       struct poll_table_struct *wait)
+{
+	struct media_request *req = filp->private_data;
+	unsigned long flags;
+	unsigned int ret = 0;
+	enum media_request_state state;
+
+	if (!(poll_requested_events(wait) & POLLPRI))
+		return 0;
+
+	spin_lock_irqsave(&req->lock, flags);
+	state = atomic_read(&req->state);
+
+	if (state == MEDIA_REQUEST_STATE_COMPLETE) {
+		ret = POLLPRI;
+		goto unlock;
+	}
+	if (state == MEDIA_REQUEST_STATE_IDLE) {
+		ret = POLLERR;
+		goto unlock;
+	}
+
+	poll_wait(filp, &req->poll_wait, wait);
+unlock:
+	spin_unlock_irqrestore(&req->lock, flags);
+	return ret;
+}
+
+static long media_request_ioctl_queue(struct media_request *req)
+{
+	struct media_device *mdev = req->mdev;
+	enum media_request_state state;
+	unsigned long flags;
+	int ret = 0;
+
+	dev_dbg(mdev->dev, "request: queue %s\n", req->debug_str);
+
+	/*
+	 * Ensure the request that is validated will be the one that gets queued
+	 * next by serialising the queueing process. This mutex is also used
+	 * to serialize with canceling a vb2 queue and with setting values such
+	 * as controls in a request.
+	 */
+	mutex_lock(&mdev->req_queue_mutex);
+
+	spin_lock_irqsave(&req->lock, flags);
+	state = atomic_cmpxchg(&req->state, MEDIA_REQUEST_STATE_IDLE,
+			       MEDIA_REQUEST_STATE_VALIDATING);
+	spin_unlock_irqrestore(&req->lock, flags);
+	if (state != MEDIA_REQUEST_STATE_IDLE) {
+		dev_dbg(mdev->dev,
+			"request: unable to queue %s, request in state %s\n",
+			req->debug_str, media_request_state_str(state));
+		mutex_unlock(&mdev->req_queue_mutex);
+		return -EBUSY;
+	}
+
+	ret = mdev->ops->req_validate(req);
+
+	/*
+	 * If the req_validate was successful, then we mark the state as QUEUED
+	 * and call req_queue. The reason we set the state first is that this
+	 * allows req_queue to unbind or complete the queued objects in case
+	 * they are immediately 'consumed'. State changes from QUEUED to another
+	 * state can only happen if either the driver changes the state or if
+	 * the user cancels the vb2 queue. The driver can only change the state
+	 * after each object is queued through the req_queue op (and note that
+	 * that op cannot fail), so setting the state to QUEUED up front is
+	 * safe.
+	 *
+	 * The other reason for changing the state is if the vb2 queue is
+	 * canceled, and that uses the req_queue_mutex which is still locked
+	 * while req_queue is called, so that's safe as well.
+	 */
+	atomic_set(&req->state,
+		   ret ? MEDIA_REQUEST_STATE_IDLE : MEDIA_REQUEST_STATE_QUEUED);
+
+	if (!ret)
+		mdev->ops->req_queue(req);
+
+	mutex_unlock(&mdev->req_queue_mutex);
+
+	if (ret) {
+		dev_dbg(mdev->dev, "request: can't queue %s (%d)\n",
+			req->debug_str, ret);
+	} else {
+		media_request_get(req);
+	}
+
+	return ret;
+}
+
+static long media_request_ioctl_reinit(struct media_request *req)
+{
+	struct media_device *mdev = req->mdev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&req->lock, flags);
+	if (atomic_read(&req->state) != MEDIA_REQUEST_STATE_IDLE &&
+	    atomic_read(&req->state) != MEDIA_REQUEST_STATE_COMPLETE) {
+		dev_dbg(mdev->dev,
+			"request: %s not in idle or complete state, cannot reinit\n",
+			req->debug_str);
+		spin_unlock_irqrestore(&req->lock, flags);
+		return -EBUSY;
+	}
+	atomic_set(&req->state, MEDIA_REQUEST_STATE_CLEANING);
+	spin_unlock_irqrestore(&req->lock, flags);
+
+	media_request_clean(req);
+
+	atomic_set(&req->state, MEDIA_REQUEST_STATE_IDLE);
+
+	return 0;
+}
+
+static long media_request_ioctl(struct file *filp, unsigned int cmd,
+				unsigned long arg)
+{
+	struct media_request *req = filp->private_data;
+
+	switch (cmd) {
+	case MEDIA_REQUEST_IOC_QUEUE:
+		return media_request_ioctl_queue(req);
+	case MEDIA_REQUEST_IOC_REINIT:
+		return media_request_ioctl_reinit(req);
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+
+static const struct file_operations request_fops = {
+	.owner = THIS_MODULE,
+	.poll = media_request_poll,
+	.unlocked_ioctl = media_request_ioctl,
+	.release = media_request_close,
+};
+
+int media_request_alloc(struct media_device *mdev,
+			struct media_request_alloc *alloc)
+{
+	struct media_request *req;
+	struct file *filp;
+	char comm[TASK_COMM_LEN];
+	int fd;
+	int ret;
+
+	/* Either both are NULL or both are non-NULL */
+	if (WARN_ON(!mdev->ops->req_alloc ^ !mdev->ops->req_free))
+		return -ENOMEM;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC);
+	if (IS_ERR(filp)) {
+		ret = PTR_ERR(filp);
+		goto err_put_fd;
+	}
+
+	if (mdev->ops->req_alloc)
+		req = mdev->ops->req_alloc(mdev);
+	else
+		req = kzalloc(sizeof(*req), GFP_KERNEL);
+	if (!req) {
+		ret = -ENOMEM;
+		goto err_fput;
+	}
+
+	filp->private_data = req;
+	req->mdev = mdev;
+	atomic_set(&req->state, MEDIA_REQUEST_STATE_IDLE);
+	req->num_incomplete_objects = 0;
+	kref_init(&req->kref);
+	INIT_LIST_HEAD(&req->objects);
+	spin_lock_init(&req->lock);
+	init_waitqueue_head(&req->poll_wait);
+
+	alloc->fd = fd;
+
+	get_task_comm(comm, current);
+	snprintf(req->debug_str, sizeof(req->debug_str), "%s:%d",
+		 comm, fd);
+	dev_dbg(mdev->dev, "request: allocated %s\n", req->debug_str);
+
+	fd_install(fd, filp);
+
+	return 0;
+
+err_fput:
+	fput(filp);
+
+err_put_fd:
+	put_unused_fd(fd);
+
+	return ret;
+}
+
+static void media_request_object_release(struct kref *kref)
+{
+	struct media_request_object *obj =
+		container_of(kref, struct media_request_object, kref);
+	struct media_request *req = obj->req;
+
+	if (req)
+		media_request_object_unbind(obj);
+	obj->ops->release(obj);
+}
+
+void media_request_object_put(struct media_request_object *obj)
+{
+	kref_put(&obj->kref, media_request_object_release);
+}
+EXPORT_SYMBOL_GPL(media_request_object_put);
+
+void media_request_object_init(struct media_request_object *obj)
+{
+	obj->ops = NULL;
+	obj->req = NULL;
+	obj->priv = NULL;
+	obj->completed = false;
+	INIT_LIST_HEAD(&obj->list);
+	kref_init(&obj->kref);
+}
+EXPORT_SYMBOL_GPL(media_request_object_init);
+
+int media_request_object_bind(struct media_request *req,
+			      const struct media_request_object_ops *ops,
+			      void *priv,
+			      struct media_request_object *obj)
+{
+	unsigned long flags;
+	int ret = -EBUSY;
+
+	if (WARN_ON(!ops->release || !ops->cancel))
+		return -EPERM;
+
+	obj->req = req;
+	obj->ops = ops;
+	obj->priv = priv;
+	spin_lock_irqsave(&req->lock, flags);
+	if (WARN_ON(atomic_read(&req->state) != MEDIA_REQUEST_STATE_IDLE))
+		goto unlock;
+	list_add_tail(&obj->list, &req->objects);
+	req->num_incomplete_objects++;
+	ret = 0;
+unlock:
+	spin_unlock_irqrestore(&req->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(media_request_object_bind);
+
+void media_request_object_unbind(struct media_request_object *obj)
+{
+	struct media_request *req = obj->req;
+	enum media_request_state state;
+	unsigned long flags;
+	bool completed = false;
+
+	if (WARN_ON(!req))
+		return;
+
+	spin_lock_irqsave(&req->lock, flags);
+	list_del(&obj->list);
+	obj->req = NULL;
+
+	state = atomic_read(&req->state);
+
+	if (state == MEDIA_REQUEST_STATE_COMPLETE ||
+	    state == MEDIA_REQUEST_STATE_CLEANING)
+		goto unlock;
+
+	if (WARN_ON(state == MEDIA_REQUEST_STATE_VALIDATING))
+		goto unlock;
+
+	if (WARN_ON(!req->num_incomplete_objects))
+		goto unlock;
+
+	req->num_incomplete_objects--;
+	if (state == MEDIA_REQUEST_STATE_QUEUED &&
+	    !req->num_incomplete_objects) {
+		atomic_set(&req->state, MEDIA_REQUEST_STATE_COMPLETE);
+		completed = true;
+		wake_up_interruptible_all(&req->poll_wait);
+	}
+unlock:
+	spin_unlock_irqrestore(&req->lock, flags);
+	if (obj->ops->unbind)
+		obj->ops->unbind(obj);
+	if (completed)
+		media_request_put(req);
+}
+EXPORT_SYMBOL_GPL(media_request_object_unbind);
+
+void media_request_object_complete(struct media_request_object *obj)
+{
+	struct media_request *req = obj->req;
+	unsigned long flags;
+	bool completed = false;
+
+	spin_lock_irqsave(&req->lock, flags);
+	if (obj->completed)
+		goto unlock;
+	obj->completed = true;
+	if (WARN_ON(!req->num_incomplete_objects) ||
+	    WARN_ON(atomic_read(&req->state) != MEDIA_REQUEST_STATE_QUEUED))
+		goto unlock;
+
+	if (!--req->num_incomplete_objects) {
+		atomic_set(&req->state, MEDIA_REQUEST_STATE_COMPLETE);
+		wake_up_interruptible_all(&req->poll_wait);
+		completed = true;
+	}
+unlock:
+	spin_unlock_irqrestore(&req->lock, flags);
+	if (completed)
+		media_request_put(req);
+}
+EXPORT_SYMBOL_GPL(media_request_object_complete);
diff --git a/include/media/media-device.h b/include/media/media-device.h
index bcc6ec434f1f..ae846208be51 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -27,6 +27,7 @@
 
 struct ida;
 struct device;
+struct media_device;
 
 /**
  * struct media_entity_notify - Media Entity Notify
@@ -50,10 +51,22 @@ struct media_entity_notify {
  * struct media_device_ops - Media device operations
  * @link_notify: Link state change notification callback. This callback is
  *		 called with the graph_mutex held.
+ * @req_alloc: Allocate a request
+ * @req_free: Free a request
+ * @req_validate: Validate a request, but do not queue yet
+ * @req_queue: Queue a validated request, cannot fail. If something goes
+ *	       wrong when queueing this request then it should be marked
+ *	       as such internally in the driver and any related buffers
+ *	       will eventually return to userspace with V4L2_BUF_FLAG_ERROR
+ *	       set.
  */
 struct media_device_ops {
 	int (*link_notify)(struct media_link *link, u32 flags,
 			   unsigned int notification);
+	struct media_request *(*req_alloc)(struct media_device *mdev);
+	void (*req_free)(struct media_request *req);
+	int (*req_validate)(struct media_request *req);
+	void (*req_queue)(struct media_request *req);
 };
 
 /**
@@ -88,6 +101,8 @@ struct media_device_ops {
  * @disable_source: Disable Source Handler function pointer
  *
  * @ops:	Operation handler callbacks
+ * @req_queue_mutex: Serialise the MEDIA_REQUEST_IOC_QUEUE ioctl w.r.t. this
+ *		     media device.
  *
  * This structure represents an abstract high-level media device. It allows easy
  * access to entities and provides basic media device-level support. The
@@ -158,6 +173,8 @@ struct media_device {
 	void (*disable_source)(struct media_entity *entity);
 
 	const struct media_device_ops *ops;
+
+	struct mutex req_queue_mutex;
 };
 
 /* We don't need to include pci.h or usb.h here */
diff --git a/include/media/media-request.h b/include/media/media-request.h
new file mode 100644
index 000000000000..9051dfbc7d30
--- /dev/null
+++ b/include/media/media-request.h
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Media device request objects
+ *
+ * Copyright (C) 2018 Intel Corporation
+ *
+ * Author: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
+ */
+
+#ifndef MEDIA_REQUEST_H
+#define MEDIA_REQUEST_H
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/atomic.h>
+
+#include <media/media-device.h>
+
+/**
+ * enum media_request_state - media request state
+ *
+ * @MEDIA_REQUEST_STATE_IDLE:		Idle
+ * @MEDIA_REQUEST_STATE_VALIDATING:	Validating the request, no state changes
+ *					allowed
+ * @MEDIA_REQUEST_STATE_QUEUED:		Queued
+ * @MEDIA_REQUEST_STATE_COMPLETE:	Completed, the request is done
+ * @MEDIA_REQUEST_STATE_CLEANING:	Cleaning, the request is being re-inited
+ */
+enum media_request_state {
+	MEDIA_REQUEST_STATE_IDLE,
+	MEDIA_REQUEST_STATE_VALIDATING,
+	MEDIA_REQUEST_STATE_QUEUED,
+	MEDIA_REQUEST_STATE_COMPLETE,
+	MEDIA_REQUEST_STATE_CLEANING,
+};
+
+struct media_request_object;
+
+/**
+ * struct media_request - Media device request
+ * @mdev: Media device this request belongs to
+ * @kref: Reference count
+ * @debug_str: Prefix for debug messages (process name:fd)
+ * @state: The state of the request
+ * @objects: List of @struct media_request_object request objects
+ * @num_objects: The number of objects in the request
+ * @num_incompleted_objects: The number of incomplete objects in the request
+ * @poll_wait: Wait queue for poll
+ * @lock: Serializes access to this struct
+ */
+struct media_request {
+	struct media_device *mdev;
+	struct kref kref;
+	char debug_str[TASK_COMM_LEN + 11];
+	atomic_t state;
+	struct list_head objects;
+	unsigned int num_incomplete_objects;
+	struct wait_queue_head poll_wait;
+	spinlock_t lock;
+};
+
+#ifdef CONFIG_MEDIA_CONTROLLER
+
+static inline void media_request_get(struct media_request *req)
+{
+	kref_get(&req->kref);
+}
+
+void media_request_put(struct media_request *req);
+void media_request_cancel(struct media_request *req);
+
+int media_request_alloc(struct media_device *mdev,
+			struct media_request_alloc *alloc);
+#else
+static inline void media_request_get(struct media_request *req)
+{
+}
+
+static inline void media_request_put(struct media_request *req)
+{
+}
+
+static inline void media_request_cancel(struct media_request *req)
+{
+}
+
+#endif
+
+struct media_request_object_ops {
+	int (*prepare)(struct media_request_object *object);
+	void (*unprepare)(struct media_request_object *object);
+	void (*queue)(struct media_request_object *object);
+	void (*unbind)(struct media_request_object *object);
+	void (*cancel)(struct media_request_object *object);
+	void (*release)(struct media_request_object *object);
+};
+
+/**
+ * struct media_request_object - An opaque object that belongs to a media
+ *				 request
+ *
+ * @ops: object's operations
+ * @priv: object's priv pointer
+ * @req: the request this object belongs to (can be NULL)
+ * @list: List entry of the object for @struct media_request
+ * @kref: Reference count of the object, acquire before releasing req->lock
+ * @completed: If true, then this object was completed.
+ *
+ * An object related to the request. This struct is embedded in the
+ * larger object data.
+ */
+struct media_request_object {
+	const struct media_request_object_ops *ops;
+	void *priv;
+	struct media_request *req;
+	struct list_head list;
+	struct kref kref;
+	bool completed;
+};
+
+#ifdef CONFIG_MEDIA_CONTROLLER
+static inline void media_request_object_get(struct media_request_object *obj)
+{
+	kref_get(&obj->kref);
+}
+
+/**
+ * media_request_object_put - Put a media request object
+ *
+ * @obj: The object
+ *
+ * Put a media request object. Once all references are gone, the
+ * object's memory is released.
+ */
+void media_request_object_put(struct media_request_object *obj);
+
+/**
+ * media_request_object_init - Initialise a media request object
+ *
+ * Initialise a media request object. The object will be released using the
+ * release callback of the ops once it has no references (this function
+ * initialises references to one).
+ */
+void media_request_object_init(struct media_request_object *obj);
+
+/**
+ * media_request_object_bind - Bind a media request object to a request
+ */
+int media_request_object_bind(struct media_request *req,
+			      const struct media_request_object_ops *ops,
+			      void *priv,
+			      struct media_request_object *obj);
+
+void media_request_object_unbind(struct media_request_object *obj);
+
+/**
+ * media_request_object_complete - Mark the media request object as complete
+ */
+void media_request_object_complete(struct media_request_object *obj);
+#else
+static inline void media_request_object_get(struct media_request_object *obj)
+{
+}
+
+static inline void media_request_object_put(struct media_request_object *obj)
+{
+}
+
+static inline void media_request_object_init(struct media_request_object *obj)
+{
+	obj->ops = NULL;
+	obj->req = NULL;
+}
+
+static inline int media_request_object_bind(struct media_request *req,
+			       const struct media_request_object_ops *ops,
+			       void *priv,
+			       struct media_request_object *obj)
+{
+	return 0;
+}
+
+static inline void media_request_object_unbind(struct media_request_object *obj)
+{
+}
+
+static inline void media_request_object_complete(struct media_request_object *obj)
+{
+}
+#endif
+
+#endif
-- 
2.17.0




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