/*
   * Memory-to-memory device framework for Video for Linux 2 and videobuf.
   *
   * Helper functions for devices that use videobuf buffers for both their
   * source and destination.
   *
   * Copyright (c) 2009-2010 Samsung Electronics Co., Ltd.

   * Pawel Osciak, <pawel@osciak.com>

   * Marek Szyprowski, <m.szyprowski@samsung.com>
   *
   * 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 the
   * Free Software Foundation; either version 2 of the License, or (at your
   * option) any later version.
   */
  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/slab.h>

  #include <media/videobuf2-core.h>

  #include <media/v4l2-mem2mem.h>
  
  MODULE_DESCRIPTION("Mem to mem device framework for videobuf");

  MODULE_AUTHOR("Pawel Osciak, <pawel@osciak.com>");

  MODULE_LICENSE("GPL");
  
  static bool debug;
  module_param(debug, bool, 0644);
  
  #define dprintk(fmt, arg...)						\
  	do {								\
  		if (debug)						\
  			printk(KERN_DEBUG "%s: " fmt, __func__, ## arg);\
  	} while (0)
  
  
  /* Instance is already queued on the job_queue */
  #define TRANS_QUEUED		(1 << 0)
  /* Instance is currently running in hardware */
  #define TRANS_RUNNING		(1 << 1)
  
  
  /* Offset base for buffers on the destination queue - used to distinguish
   * between source and destination buffers when mmapping - they receive the same
   * offsets but for different queues */
  #define DST_QUEUE_OFF_BASE	(1 << 30)
  
  
  /**
   * struct v4l2_m2m_dev - per-device context
   * @curr_ctx:		currently running instance
   * @job_queue:		instances queued to run
   * @job_spinlock:	protects job_queue
   * @m2m_ops:		driver callbacks
   */
  struct v4l2_m2m_dev {
  	struct v4l2_m2m_ctx	*curr_ctx;
  
  	struct list_head	job_queue;
  	spinlock_t		job_spinlock;
  
  	struct v4l2_m2m_ops	*m2m_ops;
  };
  
  static struct v4l2_m2m_queue_ctx *get_queue_ctx(struct v4l2_m2m_ctx *m2m_ctx,
  						enum v4l2_buf_type type)
  {

  	if (V4L2_TYPE_IS_OUTPUT(type))

  		return &m2m_ctx->out_q_ctx;

  	else
  		return &m2m_ctx->cap_q_ctx;

  }
  
  /**

   * v4l2_m2m_get_vq() - return vb2_queue for the given type

   */

  struct vb2_queue *v4l2_m2m_get_vq(struct v4l2_m2m_ctx *m2m_ctx,

  				       enum v4l2_buf_type type)
  {
  	struct v4l2_m2m_queue_ctx *q_ctx;
  
  	q_ctx = get_queue_ctx(m2m_ctx, type);
  	if (!q_ctx)
  		return NULL;
  
  	return &q_ctx->q;
  }
  EXPORT_SYMBOL(v4l2_m2m_get_vq);
  
  /**
   * v4l2_m2m_next_buf() - return next buffer from the list of ready buffers
   */

  void *v4l2_m2m_next_buf(struct v4l2_m2m_queue_ctx *q_ctx)

  {

  	struct v4l2_m2m_buffer *b = NULL;

  	unsigned long flags;

  	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);

  	if (list_empty(&q_ctx->rdy_queue)) {
  		spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
  		return NULL;
  	}

  	b = list_entry(q_ctx->rdy_queue.next, struct v4l2_m2m_buffer, list);

  	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
  	return &b->vb;

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_next_buf);
  
  /**
   * v4l2_m2m_buf_remove() - take off a buffer from the list of ready buffers and
   * return it
   */

  void *v4l2_m2m_buf_remove(struct v4l2_m2m_queue_ctx *q_ctx)

  {

  	struct v4l2_m2m_buffer *b = NULL;

  	unsigned long flags;

  	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);

  	if (list_empty(&q_ctx->rdy_queue)) {
  		spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);
  		return NULL;

  	}

  	b = list_entry(q_ctx->rdy_queue.next, struct v4l2_m2m_buffer, list);
  	list_del(&b->list);
  	q_ctx->num_rdy--;

  	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);

  	return &b->vb;

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_buf_remove);
  
  /*
   * Scheduling handlers
   */
  
  /**
   * v4l2_m2m_get_curr_priv() - return driver private data for the currently
   * running instance or NULL if no instance is running
   */
  void *v4l2_m2m_get_curr_priv(struct v4l2_m2m_dev *m2m_dev)
  {
  	unsigned long flags;
  	void *ret = NULL;
  
  	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
  	if (m2m_dev->curr_ctx)
  		ret = m2m_dev->curr_ctx->priv;
  	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  
  	return ret;
  }
  EXPORT_SYMBOL(v4l2_m2m_get_curr_priv);
  
  /**
   * v4l2_m2m_try_run() - select next job to perform and run it if possible
   *
   * Get next transaction (if present) from the waiting jobs list and run it.
   */
  static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
  	if (NULL != m2m_dev->curr_ctx) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  		dprintk("Another instance is running, won't run now
  ");
  		return;
  	}
  
  	if (list_empty(&m2m_dev->job_queue)) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  		dprintk("No job pending
  ");
  		return;
  	}
  
  	m2m_dev->curr_ctx = list_entry(m2m_dev->job_queue.next,
  				   struct v4l2_m2m_ctx, queue);
  	m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
  	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  
  	m2m_dev->m2m_ops->device_run(m2m_dev->curr_ctx->priv);
  }
  
  /**
   * v4l2_m2m_try_schedule() - check whether an instance is ready to be added to
   * the pending job queue and add it if so.
   * @m2m_ctx:	m2m context assigned to the instance to be checked
   *
   * There are three basic requirements an instance has to meet to be able to run:
   * 1) at least one source buffer has to be queued,
   * 2) at least one destination buffer has to be queued,
   * 3) streaming has to be on.
   *
   * There may also be additional, custom requirements. In such case the driver
   * should supply a custom callback (job_ready in v4l2_m2m_ops) that should
   * return 1 if the instance is ready.
   * An example of the above could be an instance that requires more than one
   * src/dst buffer per transaction.
   */
  static void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx)
  {
  	struct v4l2_m2m_dev *m2m_dev;
  	unsigned long flags_job, flags;
  
  	m2m_dev = m2m_ctx->m2m_dev;
  	dprintk("Trying to schedule a job for m2m_ctx: %p
  ", m2m_ctx);
  
  	if (!m2m_ctx->out_q_ctx.q.streaming
  	    || !m2m_ctx->cap_q_ctx.q.streaming) {
  		dprintk("Streaming needs to be on for both queues
  ");
  		return;
  	}
  
  	spin_lock_irqsave(&m2m_dev->job_spinlock, flags_job);
  	if (m2m_ctx->job_flags & TRANS_QUEUED) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
  		dprintk("On job queue already
  ");
  		return;
  	}

  	spin_lock_irqsave(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);

  	if (list_empty(&m2m_ctx->out_q_ctx.rdy_queue)) {

  		spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);

  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
  		dprintk("No input buffers available
  ");
  		return;
  	}
  	if (list_empty(&m2m_ctx->cap_q_ctx.rdy_queue)) {

  		spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);

  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
  		dprintk("No output buffers available
  ");
  		return;
  	}

  	spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);

  
  	if (m2m_dev->m2m_ops->job_ready
  		&& (!m2m_dev->m2m_ops->job_ready(m2m_ctx->priv))) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
  		dprintk("Driver not ready
  ");
  		return;
  	}
  
  	list_add_tail(&m2m_ctx->queue, &m2m_dev->job_queue);
  	m2m_ctx->job_flags |= TRANS_QUEUED;
  
  	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags_job);
  
  	v4l2_m2m_try_run(m2m_dev);
  }
  
  /**
   * v4l2_m2m_job_finish() - inform the framework that a job has been finished
   * and have it clean up
   *
   * Called by a driver to yield back the device after it has finished with it.
   * Should be called as soon as possible after reaching a state which allows
   * other instances to take control of the device.
   *
   * This function has to be called only after device_run() callback has been
   * called on the driver. To prevent recursion, it should not be called directly
   * from the device_run() callback though.
   */
  void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
  			 struct v4l2_m2m_ctx *m2m_ctx)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
  	if (!m2m_dev->curr_ctx || m2m_dev->curr_ctx != m2m_ctx) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  		dprintk("Called by an instance not currently running
  ");
  		return;
  	}
  
  	list_del(&m2m_dev->curr_ctx->queue);
  	m2m_dev->curr_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);

  	wake_up(&m2m_dev->curr_ctx->finished);

  	m2m_dev->curr_ctx = NULL;
  
  	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  
  	/* This instance might have more buffers ready, but since we do not
  	 * allow more than one job on the job_queue per instance, each has
  	 * to be scheduled separately after the previous one finishes. */
  	v4l2_m2m_try_schedule(m2m_ctx);
  	v4l2_m2m_try_run(m2m_dev);
  }
  EXPORT_SYMBOL(v4l2_m2m_job_finish);
  
  /**
   * v4l2_m2m_reqbufs() - multi-queue-aware REQBUFS multiplexer
   */
  int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		     struct v4l2_requestbuffers *reqbufs)
  {

  	struct vb2_queue *vq;

  
  	vq = v4l2_m2m_get_vq(m2m_ctx, reqbufs->type);

  	return vb2_reqbufs(vq, reqbufs);

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_reqbufs);
  
  /**
   * v4l2_m2m_querybuf() - multi-queue-aware QUERYBUF multiplexer
   *
   * See v4l2_m2m_mmap() documentation for details.
   */
  int v4l2_m2m_querybuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		      struct v4l2_buffer *buf)
  {

  	struct vb2_queue *vq;
  	int ret = 0;
  	unsigned int i;

  
  	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);

  	ret = vb2_querybuf(vq, buf);
  
  	/* Adjust MMAP memory offsets for the CAPTURE queue */
  	if (buf->memory == V4L2_MEMORY_MMAP && !V4L2_TYPE_IS_OUTPUT(vq->type)) {
  		if (V4L2_TYPE_IS_MULTIPLANAR(vq->type)) {
  			for (i = 0; i < buf->length; ++i)
  				buf->m.planes[i].m.mem_offset
  					+= DST_QUEUE_OFF_BASE;
  		} else {
  			buf->m.offset += DST_QUEUE_OFF_BASE;
  		}

  	}
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_querybuf);
  
  /**
   * v4l2_m2m_qbuf() - enqueue a source or destination buffer, depending on
   * the type
   */
  int v4l2_m2m_qbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		  struct v4l2_buffer *buf)
  {

  	struct vb2_queue *vq;

  	int ret;
  
  	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);

  	ret = vb2_qbuf(vq, buf);

  	if (!ret)
  		v4l2_m2m_try_schedule(m2m_ctx);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_qbuf);
  
  /**
   * v4l2_m2m_dqbuf() - dequeue a source or destination buffer, depending on
   * the type
   */
  int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		   struct v4l2_buffer *buf)
  {

  	struct vb2_queue *vq;

  
  	vq = v4l2_m2m_get_vq(m2m_ctx, buf->type);

  	return vb2_dqbuf(vq, buf, file->f_flags & O_NONBLOCK);

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
  
  /**
   * v4l2_m2m_streamon() - turn on streaming for a video queue
   */
  int v4l2_m2m_streamon(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		      enum v4l2_buf_type type)
  {

  	struct vb2_queue *vq;

  	int ret;
  
  	vq = v4l2_m2m_get_vq(m2m_ctx, type);

  	ret = vb2_streamon(vq, type);

  	if (!ret)
  		v4l2_m2m_try_schedule(m2m_ctx);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_streamon);
  
  /**
   * v4l2_m2m_streamoff() - turn off streaming for a video queue
   */
  int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  		       enum v4l2_buf_type type)
  {

  	struct vb2_queue *vq;

  
  	vq = v4l2_m2m_get_vq(m2m_ctx, type);

  	return vb2_streamoff(vq, type);

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_streamoff);
  
  /**
   * v4l2_m2m_poll() - poll replacement, for destination buffers only
   *
   * Call from the driver's poll() function. Will poll both queues. If a buffer
   * is available to dequeue (with dqbuf) from the source queue, this will
   * indicate that a non-blocking write can be performed, while read will be
   * returned in case of the destination queue.
   */
  unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  			   struct poll_table_struct *wait)
  {

  	struct vb2_queue *src_q, *dst_q;
  	struct vb2_buffer *src_vb = NULL, *dst_vb = NULL;

  	unsigned int rc = 0;

  	unsigned long flags;

  
  	src_q = v4l2_m2m_get_src_vq(m2m_ctx);
  	dst_q = v4l2_m2m_get_dst_vq(m2m_ctx);

  	/*
  	 * There has to be at least one buffer queued on each queued_list, which
  	 * means either in driver already or waiting for driver to claim it
  	 * and start processing.
  	 */
  	if ((!src_q->streaming || list_empty(&src_q->queued_list))
  		&& (!dst_q->streaming || list_empty(&dst_q->queued_list))) {

  		rc = POLLERR;
  		goto end;
  	}

  	if (m2m_ctx->m2m_dev->m2m_ops->unlock)
  		m2m_ctx->m2m_dev->m2m_ops->unlock(m2m_ctx->priv);
  
  	poll_wait(file, &src_q->done_wq, wait);
  	poll_wait(file, &dst_q->done_wq, wait);
  
  	if (m2m_ctx->m2m_dev->m2m_ops->lock)
  		m2m_ctx->m2m_dev->m2m_ops->lock(m2m_ctx->priv);
  
  	spin_lock_irqsave(&src_q->done_lock, flags);
  	if (!list_empty(&src_q->done_list))
  		src_vb = list_first_entry(&src_q->done_list, struct vb2_buffer,
  						done_entry);
  	if (src_vb && (src_vb->state == VB2_BUF_STATE_DONE
  			|| src_vb->state == VB2_BUF_STATE_ERROR))
  		rc |= POLLOUT | POLLWRNORM;
  	spin_unlock_irqrestore(&src_q->done_lock, flags);
  
  	spin_lock_irqsave(&dst_q->done_lock, flags);
  	if (!list_empty(&dst_q->done_list))
  		dst_vb = list_first_entry(&dst_q->done_list, struct vb2_buffer,
  						done_entry);
  	if (dst_vb && (dst_vb->state == VB2_BUF_STATE_DONE
  			|| dst_vb->state == VB2_BUF_STATE_ERROR))
  		rc |= POLLIN | POLLRDNORM;
  	spin_unlock_irqrestore(&dst_q->done_lock, flags);

  
  end:

  	return rc;
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_poll);
  
  /**
   * v4l2_m2m_mmap() - source and destination queues-aware mmap multiplexer
   *
   * Call from driver's mmap() function. Will handle mmap() for both queues
   * seamlessly for videobuffer, which will receive normal per-queue offsets and
   * proper videobuf queue pointers. The differentiation is made outside videobuf
   * by adding a predefined offset to buffers from one of the queues and
   * subtracting it before passing it back to videobuf. Only drivers (and
   * thus applications) receive modified offsets.
   */
  int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
  			 struct vm_area_struct *vma)
  {
  	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;

  	struct vb2_queue *vq;

  
  	if (offset < DST_QUEUE_OFF_BASE) {
  		vq = v4l2_m2m_get_src_vq(m2m_ctx);
  	} else {
  		vq = v4l2_m2m_get_dst_vq(m2m_ctx);
  		vma->vm_pgoff -= (DST_QUEUE_OFF_BASE >> PAGE_SHIFT);
  	}

  	return vb2_mmap(vq, vma);

  }
  EXPORT_SYMBOL(v4l2_m2m_mmap);
  
  /**
   * v4l2_m2m_init() - initialize per-driver m2m data
   *
   * Usually called from driver's probe() function.
   */
  struct v4l2_m2m_dev *v4l2_m2m_init(struct v4l2_m2m_ops *m2m_ops)
  {
  	struct v4l2_m2m_dev *m2m_dev;
  
  	if (!m2m_ops)
  		return ERR_PTR(-EINVAL);
  
  	BUG_ON(!m2m_ops->device_run);
  	BUG_ON(!m2m_ops->job_abort);
  
  	m2m_dev = kzalloc(sizeof *m2m_dev, GFP_KERNEL);
  	if (!m2m_dev)
  		return ERR_PTR(-ENOMEM);
  
  	m2m_dev->curr_ctx = NULL;
  	m2m_dev->m2m_ops = m2m_ops;
  	INIT_LIST_HEAD(&m2m_dev->job_queue);
  	spin_lock_init(&m2m_dev->job_spinlock);
  
  	return m2m_dev;
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_init);
  
  /**
   * v4l2_m2m_release() - cleans up and frees a m2m_dev structure
   *
   * Usually called from driver's remove() function.
   */
  void v4l2_m2m_release(struct v4l2_m2m_dev *m2m_dev)
  {
  	kfree(m2m_dev);
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_release);
  
  /**
   * v4l2_m2m_ctx_init() - allocate and initialize a m2m context
   * @priv - driver's instance private data
   * @m2m_dev - a previously initialized m2m_dev struct
   * @vq_init - a callback for queue type-specific initialization function to be
   * used for initializing videobuf_queues
   *
   * Usually called from driver's open() function.
   */

  struct v4l2_m2m_ctx *v4l2_m2m_ctx_init(struct v4l2_m2m_dev *m2m_dev,
  		void *drv_priv,
  		int (*queue_init)(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq))

  {
  	struct v4l2_m2m_ctx *m2m_ctx;
  	struct v4l2_m2m_queue_ctx *out_q_ctx, *cap_q_ctx;

  	int ret;

  
  	m2m_ctx = kzalloc(sizeof *m2m_ctx, GFP_KERNEL);
  	if (!m2m_ctx)
  		return ERR_PTR(-ENOMEM);

  	m2m_ctx->priv = drv_priv;

  	m2m_ctx->m2m_dev = m2m_dev;

  	init_waitqueue_head(&m2m_ctx->finished);

  	out_q_ctx = &m2m_ctx->out_q_ctx;
  	cap_q_ctx = &m2m_ctx->cap_q_ctx;

  
  	INIT_LIST_HEAD(&out_q_ctx->rdy_queue);
  	INIT_LIST_HEAD(&cap_q_ctx->rdy_queue);

  	spin_lock_init(&out_q_ctx->rdy_spinlock);
  	spin_lock_init(&cap_q_ctx->rdy_spinlock);

  
  	INIT_LIST_HEAD(&m2m_ctx->queue);

  	ret = queue_init(drv_priv, &out_q_ctx->q, &cap_q_ctx->q);
  
  	if (ret)
  		goto err;

  
  	return m2m_ctx;

  err:
  	kfree(m2m_ctx);
  	return ERR_PTR(ret);

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_init);
  
  /**
   * v4l2_m2m_ctx_release() - release m2m context
   *
   * Usually called from driver's release() function.
   */
  void v4l2_m2m_ctx_release(struct v4l2_m2m_ctx *m2m_ctx)
  {
  	struct v4l2_m2m_dev *m2m_dev;

  	unsigned long flags;
  
  	m2m_dev = m2m_ctx->m2m_dev;
  
  	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
  	if (m2m_ctx->job_flags & TRANS_RUNNING) {
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  		m2m_dev->m2m_ops->job_abort(m2m_ctx->priv);
  		dprintk("m2m_ctx %p running, will wait to complete", m2m_ctx);

  		wait_event(m2m_ctx->finished, !(m2m_ctx->job_flags & TRANS_RUNNING));

  	} else if (m2m_ctx->job_flags & TRANS_QUEUED) {
  		list_del(&m2m_ctx->queue);
  		m2m_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  		dprintk("m2m_ctx: %p had been on queue and was removed
  ",
  			m2m_ctx);
  	} else {
  		/* Do nothing, was not on queue/running */
  		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
  	}

  	vb2_queue_release(&m2m_ctx->cap_q_ctx.q);
  	vb2_queue_release(&m2m_ctx->out_q_ctx.q);

  
  	kfree(m2m_ctx);
  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_ctx_release);
  
  /**
   * v4l2_m2m_buf_queue() - add a buffer to the proper ready buffers list.
   *
   * Call from buf_queue(), videobuf_queue_ops callback.

   */

  void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx, struct vb2_buffer *vb)

  {

  	struct v4l2_m2m_buffer *b = container_of(vb, struct v4l2_m2m_buffer, vb);

  	struct v4l2_m2m_queue_ctx *q_ctx;

  	unsigned long flags;

  	q_ctx = get_queue_ctx(m2m_ctx, vb->vb2_queue->type);

  	if (!q_ctx)
  		return;

  	spin_lock_irqsave(&q_ctx->rdy_spinlock, flags);
  	list_add_tail(&b->list, &q_ctx->rdy_queue);

  	q_ctx->num_rdy++;

  	spin_unlock_irqrestore(&q_ctx->rdy_spinlock, flags);

  }
  EXPORT_SYMBOL_GPL(v4l2_m2m_buf_queue);