python实盘股票交易接口:v4l2 poll驱动唤醒应用等待队列

实现的驱动会调用vb2_buffer_done，唤醒q->done_wq的等待队列，此时应用即可DQBUF。

v4l2 poll驱动唤醒应用等待队列

poll调用到驱动实现的字符设备poll接口

static const struct v4l2_file_operations video_file_ops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = video_ioctl2,
	.open = video_open,
	.release = video_release,
	.poll = vb2_fop_poll,
	.mmap = vb2_fop_mmap,
	.read = vb2_fop_read,
};

vb2_fop_poll
--vb2_poll
----vb2_core_poll
------poll_wait

	if (list_empty(&q->done_list)) {
		/*
		 * If the last buffer was dequeued from a capture queue,
		 * return immediately. DQBUF will return -EPIPE.
		 */
		if (q->last_buffer_dequeued)
			return POLLIN | POLLRDNORM;

		poll_wait(file, &q->done_wq, wait);
	}

文章为作者独立观点，不代表股票交易接口观点