1 files changed, 132 insertions, 0 deletions
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 5a9597d..e5449a2 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -94,13 +94,52 @@ struct v4l2_m2m_buffer {
 	struct list_head	list;
 };
 
+/**
+ * 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);
 
+/**
+ * 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);
 
+/**
+ * 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.
+ *
+ * If a queue is buffered (for example a decoder hardware ringbuffer that has
+ * to be drained before doing streamoff), allow scheduling without v4l2 buffers
+ * on that queue.
+ *
+ * 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.
+ */
 void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx *m2m_ctx);
 
+/**
+ * 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);
 
@@ -110,38 +149,114 @@ v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
 	vb2_buffer_done(&buf->vb2_buf, state);
 }
 
+/**
+ * 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);
 
+/**
+ * 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);
 
+/**
+ * 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);
+
+/**
+ * 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);
+
+/**
+ * v4l2_m2m_prepare_buf() - prepare a source or destination buffer, depending on
+ * the type
+ */
 int v4l2_m2m_prepare_buf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 			 struct v4l2_buffer *buf);
+
+/**
+ * v4l2_m2m_create_bufs() - create a source or destination buffer, depending
+ * on the type
+ */
 int v4l2_m2m_create_bufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 			 struct v4l2_create_buffers *create);
 
+/**
+ * v4l2_m2m_expbuf() - export a source or destination buffer, depending on
+ * the type
+ */
 int v4l2_m2m_expbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		   struct v4l2_exportbuffer *eb);
 
+/**
+ * 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);
+
+/**
+ * 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);
 
+/**
+ * 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);
 
+/**
+ * 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);
 
+/**
+ * v4l2_m2m_init() - initialize per-driver m2m data
+ *
+ * Usually called from driver's probe() function.
+ */
 struct v4l2_m2m_dev *v4l2_m2m_init(const struct v4l2_m2m_ops *m2m_ops);
+
+/**
+ * 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);
 
+/**
+ * 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));
@@ -158,8 +273,18 @@ static inline void v4l2_m2m_set_dst_buffered(struct v4l2_m2m_ctx *m2m_ctx,
 	m2m_ctx->cap_q_ctx.buffered = buffered;
 }
 
+/**
+ * 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);
 
+/**
+ * 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_v4l2_buffer *vbuf);
 
@@ -187,6 +312,9 @@ unsigned int v4l2_m2m_num_dst_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
 	return m2m_ctx->cap_q_ctx.num_rdy;
 }
 
+/**
+ * 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);
 
 /**
@@ -233,6 +361,10 @@ struct vb2_queue *v4l2_m2m_get_dst_vq(struct v4l2_m2m_ctx *m2m_ctx)
 	return &m2m_ctx->cap_q_ctx.q;
 }
 
+/**
+ * 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);
 
 /**