极客笔记本讲是Camera KMD ISP子系统专题的第6讲，我们讲解CRM V4L2驱动模型。
更多资源：
| 资源 | 描述 |
|---|---|
| 在线课程 | 极客笔记在线课程 |
| 知识星球 | 星球名称：深入浅出Android Camera 星球ID: 17296815 |
| 极客笔记圈 |
V4L2重要结构体
struct v4l2_device
struct v4l2_device {
struct device *dev;
struct media_device *mdev;//属于哪个media_device
struct list_head subdevs;//保存所有的v4l2_subdev
spinlock_t lock;
char name[V4L2_DEVICE_NAME_SIZE];
void (*notify)(struct v4l2_subdev *sd,unsigned int notification, void *arg);
struct v4l2_ctrl_handler *ctrl_handler;
struct v4l2_prio_state prio;
struct kref ref;
void (*release)(struct v4l2_device *v4l2_dev);
};
struct video_device
struct video_device {
struct media_entity entity;//用于挂到media_device的entities链表上
struct v4l2_device *v4l2_dev;//指向一个v4l2_device
struct vb2_queue *queue;//video buffer queue
char name[32];//设备名
enum vfl_devnode_type vfl_type;//type of V4L2 device node(VFL_TYPE_VIDEO, VFL_TYPE_SUBDEV)
const struct v4l2_ioctl_ops *ioctl_ops;//指向 v4l2_ioctl_ops指针
}
其中，ioctl_ops如下：
struct media_device
struct media_device {
/* dev->driver_data points to this struct. */
struct device *dev;
struct media_devnode *devnode;//创建设备节点相关的
char model[32];//保存的是名字，例如:”cam-req-mgr-devnode”
struct list_head entities;//保存了所有的entity
}
struct media_entity
struct media_entity {
struct media_gobj graph_obj;//用于挂在media_device entities链表
const char *name; // entity的名字
enum media_entity_type obj_type; // MEDIA_ENTITY_TYPE_VIDEO_DEVICE, MEDIA_ENTITY_TYPE_V4L2_SUBDEV
u32 function;// CAM_DEVICE_TYPE_BASE, CAM_TFE_DEVICE_TYPE
}
struct media_gobj {
struct media_device *mdev;
u32 id;
struct list_head list; //用于挂在media_device entities链表
};
struct v4l2_subdev
struct v4l2_subdev {
struct media_entity entity;//用于挂到media_device的entities链表上
struct list_head list;//用于挂在v4l2_device的subdevs链表上
u32 flags;//标志信息，例如: V4L2_SUBDEV_FL_HAS_DEVNODE, V4L2_SUBDEV_FL_HAS_EVENTS
struct v4l2_device *v4l2_dev;//指向一个v4l2_device对象，跟主设备指向的是同一个v4l2_device对象
const struct v4l2_subdev_ops *ops;// pointer to struct &v4l2_subdev_ops
const struct v4l2_subdev_internal_ops *internal_ops;// pointer to struct &v4l2_subdev_internal_ops.
char name[V4L2_SUBDEV_NAME_SIZE];//子设备名字
struct video_device *devnode;//创建设备节点/dev/v4l2-subdevX时创建的video_device
}
CRM V4l2 驱动模型
CRM V4L2框架初始化流程(主设备)
CRM V4L2框架初始化流程(子设备)
CRM V4L2驱动模型拓扑图
CSL Layer 如何使用media entity
CRM V4L2驱动设备节点含义
/dev/video0: crm-req-mgr
/dev/v4l-subdev0: cam-cpas
/dev/v4l-subdev1: cam-isp
/dev/v4l-subdev2: cam-csiphy-driver
/dev/v4l-subdev3: cam-csiphy-driver
/dev/v4l-subdev4: cam-csiphy-driver
/dev/v4l-subdev5: cam-actuator-driver
/dev/v4l-subdev6: cam-sensor-driver
/dev/v4l-subdev7: cam-sensor-driver
/dev/v4l-subdev8: cam-sensor-driver
/dev/v4l-subdev9: cam-eeprom
/dev/v4l-subdev10: cam-eeprom
/dev/v4l-subdev11: cam-flash-dev
/dev/v4l-subdev12: cam-ope
CRM V4L2驱动设备节点含义对照
header file(entity type): include/uapi/camera/media/cam_req_mgr.h
CRM驱动ioctl调用流程
子设备驱动ioctl调用流程
