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[media] videobuf2-v4l2.h: improve documentation

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There are a few issues at the documentation: fields not documented,
bad cross refrences, etc.

Fix them.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Mauro Carvalho Chehab 2016-09-08 18:01:44 -03:00
parent 24ade5b6de
commit bf4404b482
1 changed files with 33 additions and 19 deletions
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52
include/media/videobuf2-v4l2.h
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@ -25,11 +25,13 @@
/**
* struct vb2_v4l2_buffer - video buffer information for v4l2
*
* @vb2_buf: video buffer 2
* @flags: buffer informational flags
* @field: enum v4l2_field; field order of the image in the buffer
* @timecode: frame timecode
* @sequence: sequence count of this frame
*
* Should contain enough information to be able to cover all the fields
* of struct v4l2_buffer at videodev2.h
*/
@ -53,6 +55,7 @@ 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
@ -62,6 +65,7 @@ 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
@ -70,15 +74,17 @@ 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,
*
* #) verifies the passed buffer,
* #) 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.
@ -88,53 +94,57 @@ 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
* @b: buffer structure passed from userspace to VIDIOC_QBUF() handler
* in driver
*
* Should be called from vidioc_qbuf ioctl handler of a 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
*
* #) verifies the passed buffer,
* #) 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
* #) 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.
* 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
* @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.
* 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
* @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.
* 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
*
* #) verifies the passed buffer,
* #) 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 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.
* from VIDIOC_DQBUF() handler in driver.
*/
int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
@ -144,7 +154,9 @@ int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
* @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
*
@ -159,9 +171,11 @@ int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
* @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
*
* #) verifies current state,
* #) 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.