video_device is initialized you *do* know which parent PCI device to use and
so you set dev_device to the correct PCI device.
-- flags: optional. Set to V4L2_FL_USE_FH_PRIO if you want to let the framework
- handle the VIDIOC_G/S_PRIORITY ioctls. This requires that you use struct
- v4l2_fh. Eventually this flag will disappear once all drivers use the core
- priority handling. But for now it has to be set explicitly.
-
If you use v4l2_ioctl_ops, then you should set .unlocked_ioctl to video_ioctl2
in your v4l2_file_operations struct.
struct v4l2_fh provides a way to easily keep file handle specific data
that is used by the V4L2 framework. New drivers must use struct v4l2_fh
-since it is also used to implement priority handling (VIDIOC_G/S_PRIORITY)
-if the video_device flag V4L2_FL_USE_FH_PRIO is also set.
+since it is also used to implement priority handling (VIDIOC_G/S_PRIORITY).
The users of v4l2_fh (in the V4L2 framework, not the driver) know
whether a driver uses v4l2_fh as its file->private_data pointer by
vdev->v4l2_dev = &skel->v4l2_dev;
/* Supported SDTV standards, if any */
vdev->tvnorms = SKEL_TVNORMS;
- /* If this bit is set, then the v4l2 core will provide the support
- * for the VIDIOC_G/S_PRIORITY ioctls. This flag will eventually
- * go away once all drivers have been converted to use struct v4l2_fh.
- */
- set_bit(V4L2_FL_USE_FH_PRIO, &vdev->flags);
video_set_drvdata(vdev, skel);
ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
v4l2_device 无法与特定的 PCI 设备关联,所有没有设置父设备。但当
video_device 配置后,就知道使用哪个父 PCI 设备了。
-- flags:可选。如果你要让框架处理设置 VIDIOC_G/S_PRIORITY ioctls,
- 请设置 V4L2_FL_USE_FH_PRIO。这要求你使用 v4l2_fh 结构体。
- 一旦所有驱动使用了核心的优先级处理,最终这个标志将消失。但现在它
- 必须被显式设置。
-
如果你使用 v4l2_ioctl_ops,则应该在 v4l2_file_operations 结构体中
设置 .unlocked_ioctl 指向 video_ioctl2。
-------------
v4l2_fh 结构体提供一个保存用于 V4L2 框架的文件句柄特定数据的简单方法。
-如果 video_device 的 flag 设置了 V4L2_FL_USE_FH_PRIO 标志,新驱动
+如果 video_device 标志,新驱动
必须使用 v4l2_fh 结构体,因为它也用于实现优先级处理(VIDIOC_G/S_PRIORITY)。
v4l2_fh 的用户(位于 V4l2 框架中,并非驱动)可通过测试