#include <videobuf2-core.h>

Data Fields
int(*	queue_setup )(struct vb2_queue q, const struct v4l2_format fmt, unsigned int num_buffers, unsigned int num_planes, unsigned int sizes[], void *alloc_ctxs[])

void(*	wait_prepare )(struct vb2_queue *q)

void(*	wait_finish )(struct vb2_queue *q)

int(*	buf_init )(struct vb2_buffer *vb)

int(*	buf_prepare )(struct vb2_buffer *vb)

int(*	buf_finish )(struct vb2_buffer *vb)

void(*	buf_cleanup )(struct vb2_buffer *vb)

int(*	start_streaming )(struct vb2_queue *q, unsigned int count)

int(*	stop_streaming )(struct vb2_queue *q)

void(*	buf_queue )(struct vb2_buffer *vb)

Detailed Description

struct vb2_ops - driver-specific callbacks

: called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS handlers before memory allocation, or, if *num_planes != 0, after the allocation to verify a smaller number of buffers. Driver should return the required number of buffers in *num_buffers, the required number of planes per buffer in *num_planes; the size of each plane should be set in the sizes[] array and optional per-plane allocator specific context in the alloc_ctxs[] array. When called from VIDIOC_REQBUFS, fmt == NULL, the driver has to use the currently configured format and *num_buffers is the total number of buffers, that are being allocated. When called from VIDIOC_CREATE_BUFS, fmt != NULL and it describes the target frame format. In this case *num_buffers are being allocated additionally to q->num_buffers. : release any locks taken while calling vb2 functions; it is called before an ioctl needs to wait for a new buffer to arrive; required to avoid a deadlock in blocking access type : reacquire all locks released in the previous callback; required to continue operation after sleeping while waiting for a new buffer to arrive : called once after allocating a buffer (in MMAP case) or after acquiring a new USERPTR buffer; drivers may perform additional buffer-related initialization; initialization failure (return != 0) will prevent queue setup from completing successfully; optional : called every time the buffer is queued from userspace and from the VIDIOC_PREPARE_BUF ioctl; drivers may perform any initialization required before each hardware operation in this callback; if an error is returned, the buffer will not be queued in driver; optional : called before every dequeue of the buffer back to userspace; drivers may perform any operations required before userspace accesses the buffer; optional : called once before the buffer is freed; drivers may perform any additional cleanup; optional : called once to enter 'streaming' state; the driver may receive buffers with callback before is called; the driver gets the number of already queued buffers in count parameter; driver can return an error if hardware fails or not enough buffers has been queued, in such case all buffers that have been already given by the callback are invalidated. : called when 'streaming' state must be disabled; driver should stop any DMA transactions or wait until they finish and give back all buffers it got from buf_queue() callback; may use vb2_wait_for_all_buffers() function : passes buffer vb to the driver; driver may start hardware operation on this buffer; driver should give the buffer back by calling vb2_buffer_done() function; it is allways called after calling STREAMON ioctl; might be called before start_streaming callback if user pre-queued buffers before calling STREAMON