[media] videobuf2-v4l2.h: improve documentation (bf4404b4) · Commits · e / devices / android_kernel_oneplus_sm7250

include/media/videobuf2-v4l2.h

+33 −19

Original line number	Diff line number	Diff line
		@@ -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.