[media] videobuf2-v4l2.h: improve documentation
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>
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@ -25,11 +25,13 @@
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/**
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* struct vb2_v4l2_buffer - video buffer information for v4l2
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*
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* @vb2_buf: video buffer 2
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* @flags: buffer informational flags
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* @field: enum v4l2_field; field order of the image in the buffer
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* @timecode: frame timecode
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* @sequence: sequence count of this frame
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*
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* Should contain enough information to be able to cover all the fields
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* of struct v4l2_buffer at videodev2.h
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*/
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@ -53,6 +55,7 @@ int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
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/**
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* vb2_reqbufs() - Wrapper for vb2_core_reqbufs() that also verifies
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* the memory and type values.
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*
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* @q: videobuf2 queue
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* @req: struct passed from userspace to vidioc_reqbufs handler
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* in driver
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@ -62,6 +65,7 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
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/**
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* vb2_create_bufs() - Wrapper for vb2_core_create_bufs() that also verifies
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* the memory and type values.
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*
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* @q: videobuf2 queue
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* @create: creation parameters, passed from userspace to vidioc_create_bufs
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* handler in driver
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@ -70,15 +74,17 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
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/**
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* vb2_prepare_buf() - Pass ownership of a buffer from userspace to the kernel
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*
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* @q: videobuf2 queue
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* @b: buffer structure passed from userspace to vidioc_prepare_buf
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* handler in driver
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*
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* Should be called from vidioc_prepare_buf ioctl handler of a driver.
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* This function:
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* 1) verifies the passed buffer,
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* 2) calls buf_prepare callback in the driver (if provided), in which
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* driver-specific buffer initialization can be performed,
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*
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* #) verifies the passed buffer,
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* #) calls buf_prepare callback in the driver (if provided), in which
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* driver-specific buffer initialization can be performed.
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*
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* The return values from this function are intended to be directly returned
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* from vidioc_prepare_buf handler in driver.
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@ -88,53 +94,57 @@ int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b);
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/**
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* vb2_qbuf() - Queue a buffer from userspace
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* @q: videobuf2 queue
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* @b: buffer structure passed from userspace to vidioc_qbuf handler
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* @b: buffer structure passed from userspace to VIDIOC_QBUF() handler
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* in driver
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*
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* Should be called from vidioc_qbuf ioctl handler of a driver.
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* Should be called from VIDIOC_QBUF() ioctl handler of a driver.
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*
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* This function:
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* 1) verifies the passed buffer,
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* 2) if necessary, calls buf_prepare callback in the driver (if provided), in
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*
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* #) verifies the passed buffer,
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* #) if necessary, calls buf_prepare callback in the driver (if provided), in
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* which driver-specific buffer initialization can be performed,
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* 3) if streaming is on, queues the buffer in driver by the means of buf_queue
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* #) if streaming is on, queues the buffer in driver by the means of buf_queue
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* callback for processing.
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*
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* The return values from this function are intended to be directly returned
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* from vidioc_qbuf handler in driver.
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* from VIDIOC_QBUF() handler in driver.
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*/
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int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
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/**
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* vb2_expbuf() - Export a buffer as a file descriptor
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* @q: videobuf2 queue
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* @eb: export buffer structure passed from userspace to vidioc_expbuf
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* @eb: export buffer structure passed from userspace to VIDIOC_EXPBUF()
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* handler in driver
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*
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* The return values from this function are intended to be directly returned
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* from vidioc_expbuf handler in driver.
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* from VIDIOC_EXPBUF() handler in driver.
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*/
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int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb);
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/**
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* vb2_dqbuf() - Dequeue a buffer to the userspace
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* @q: videobuf2 queue
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* @b: buffer structure passed from userspace to vidioc_dqbuf handler
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* @b: buffer structure passed from userspace to VIDIOC_DQBUF() handler
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* in driver
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* @nonblocking: if true, this call will not sleep waiting for a buffer if no
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* buffers ready for dequeuing are present. Normally the driver
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* would be passing (file->f_flags & O_NONBLOCK) here
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*
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* Should be called from vidioc_dqbuf ioctl handler of a driver.
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* Should be called from VIDIOC_DQBUF() ioctl handler of a driver.
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*
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* This function:
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* 1) verifies the passed buffer,
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* 2) calls buf_finish callback in the driver (if provided), in which
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*
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* #) verifies the passed buffer,
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* #) calls buf_finish callback in the driver (if provided), in which
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* driver can perform any additional operations that may be required before
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* returning the buffer to userspace, such as cache sync,
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* 3) the buffer struct members are filled with relevant information for
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* #) the buffer struct members are filled with relevant information for
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* the userspace.
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*
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* The return values from this function are intended to be directly returned
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* from vidioc_dqbuf handler in driver.
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* from VIDIOC_DQBUF() handler in driver.
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*/
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int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
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@ -144,7 +154,9 @@ int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
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* @type: type argument passed from userspace to vidioc_streamon handler
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*
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* Should be called from vidioc_streamon handler of a driver.
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*
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* This function:
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*
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* 1) verifies current state
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* 2) passes any previously queued buffers to the driver and starts streaming
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*
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@ -159,9 +171,11 @@ int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
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* @type: type argument passed from userspace to vidioc_streamoff handler
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*
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* Should be called from vidioc_streamoff handler of a driver.
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*
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* This function:
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* 1) verifies current state,
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* 2) stop streaming and dequeues any queued buffers, including those previously
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*
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* #) verifies current state,
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* #) stop streaming and dequeues any queued buffers, including those previously
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* passed to the driver (after waiting for the driver to finish).
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*
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* This call can be used for pausing playback.
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