[media] videobuf2-v4l2.h: get kernel-doc tags from C file

There are several functions documented at the C file. Move
them to the header, as this is the one used to build the
media books.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 150 insertions, 1 deletions

diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
index 3cc836f..01b1b71 100644
--- a/include/media/videobuf2-v4l2.h
+++ b/include/media/videobuf2-v4l2.h
@@ -49,22 +49,171 @@ struct vb2_v4l2_buffer {
 	container_of(vb, struct vb2_v4l2_buffer, vb2_buf)
 
 int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
+
+/**
+ * vb2_reqbufs() - Wrapper for vb2_core_reqbufs() that also verifies
+ * the memory and type values.
+ * @q:		videobuf2 queue
+ * @req:	struct passed from userspace to vidioc_reqbufs handler
+ *		in driver
+ */
 int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
 
+/**
+ * vb2_create_bufs() - Wrapper for vb2_core_create_bufs() that also verifies
+ * the memory and type values.
+ * @q:		videobuf2 queue
+ * @create:	creation parameters, passed from userspace to vidioc_create_bufs
+ *		handler in driver
+ */
 int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
+
+/**
+ * vb2_prepare_buf() - Pass ownership of a buffer from userspace to the kernel
+ * @q:		videobuf2 queue
+ * @b:		buffer structure passed from userspace to vidioc_prepare_buf
+ *		handler in driver
+ *
+ * Should be called from vidioc_prepare_buf ioctl handler of a driver.
+ * This function:
+ * 1) verifies the passed buffer,
+ * 2) calls buf_prepare callback in the driver (if provided), in which
+ *    driver-specific buffer initialization can be performed,
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_prepare_buf handler in driver.
+ */
 int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b);
 
+/**
+ * vb2_qbuf() - Queue a buffer from userspace
+ * @q:		videobuf2 queue
+ * @b:		buffer structure passed from userspace to vidioc_qbuf handler
+ *		in driver
+ *
+ * Should be called from vidioc_qbuf ioctl handler of a driver.
+ * This function:
+ * 1) verifies the passed buffer,
+ * 2) if necessary, calls buf_prepare callback in the driver (if provided), in
+ *    which driver-specific buffer initialization can be performed,
+ * 3) if streaming is on, queues the buffer in driver by the means of buf_queue
+ *    callback for processing.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_qbuf handler in driver.
+ */
 int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
+
+/**
+ * vb2_expbuf() - Export a buffer as a file descriptor
+ * @q:		videobuf2 queue
+ * @eb:		export buffer structure passed from userspace to vidioc_expbuf
+ *		handler in driver
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_expbuf handler in driver.
+ */
 int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb);
+
+/**
+ * vb2_dqbuf() - Dequeue a buffer to the userspace
+ * @q:		videobuf2 queue
+ * @b:		buffer structure passed from userspace to vidioc_dqbuf handler
+ *		in driver
+ * @nonblocking: if true, this call will not sleep waiting for a buffer if no
+ *		 buffers ready for dequeuing are present. Normally the driver
+ *		 would be passing (file->f_flags & O_NONBLOCK) here
+ *
+ * Should be called from vidioc_dqbuf ioctl handler of a driver.
+ * This function:
+ * 1) verifies the passed buffer,
+ * 2) calls buf_finish callback in the driver (if provided), in which
+ *    driver can perform any additional operations that may be required before
+ *    returning the buffer to userspace, such as cache sync,
+ * 3) the buffer struct members are filled with relevant information for
+ *    the userspace.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_dqbuf handler in driver.
+ */
 int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
 
+/**
+ * vb2_streamon - start streaming
+ * @q:		videobuf2 queue
+ * @type:	type argument passed from userspace to vidioc_streamon handler
+ *
+ * Should be called from vidioc_streamon handler of a driver.
+ * This function:
+ * 1) verifies current state
+ * 2) passes any previously queued buffers to the driver and starts streaming
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_streamon handler in the driver.
+ */
 int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
+
+/**
+ * vb2_streamoff - stop streaming
+ * @q:		videobuf2 queue
+ * @type:	type argument passed from userspace to vidioc_streamoff handler
+ *
+ * Should be called from vidioc_streamoff handler of a driver.
+ * This function:
+ * 1) verifies current state,
+ * 2) stop streaming and dequeues any queued buffers, including those previously
+ *    passed to the driver (after waiting for the driver to finish).
+ *
+ * This call can be used for pausing playback.
+ * The return values from this function are intended to be directly returned
+ * from vidioc_streamoff handler in the driver
+ */
 int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
 
+/**
+ * vb2_queue_init() - initialize a videobuf2 queue
+ * @q:		videobuf2 queue; this structure should be allocated in driver
+ *
+ * The vb2_queue structure should be allocated by the driver. The driver is
+ * responsible of clearing it's content and setting initial values for some
+ * required entries before calling this function.
+ * q->ops, q->mem_ops, q->type and q->io_modes are mandatory. Please refer
+ * to the struct vb2_queue description in include/media/videobuf2-core.h
+ * for more information.
+ */
 int __must_check vb2_queue_init(struct vb2_queue *q);
+
+/**
+ * vb2_queue_release() - stop streaming, release the queue and free memory
+ * @q:		videobuf2 queue
+ *
+ * This function stops streaming and performs necessary clean ups, including
+ * freeing video buffer memory. The driver is responsible for freeing
+ * the vb2_queue structure itself.
+ */
 void vb2_queue_release(struct vb2_queue *q);
+
+/**
+ * vb2_poll() - implements poll userspace operation
+ * @q:		videobuf2 queue
+ * @file:	file argument passed to the poll file operation handler
+ * @wait:	wait argument passed to the poll file operation handler
+ *
+ * This function implements poll file operation handler for a driver.
+ * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
+ * be informed that the file descriptor of a video device is available for
+ * reading.
+ * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
+ * will be reported as available for writing.
+ *
+ * If the driver uses struct v4l2_fh, then vb2_poll() will also check for any
+ * pending events.
+ *
+ * The return values from this function are intended to be directly returned
+ * from poll handler in driver.
+ */
 unsigned int vb2_poll(struct vb2_queue *q, struct file *file,
-		poll_table *wait);
+		      poll_table *wait);
 
 /*
  * The following functions are not part of the vb2 core API, but are simple