Camera

先看一下抽象层的主要流程：

首先启动一个守护进程

int qcamsvr_start(void)( qcamsvr.c)

{

1. server_fd = open(server_dev_name, O_RDWR);//打开服务对应的文件节点

2. if (mctl_load_comps()) //加载所有需要的组件

3. rc = qcamsvr_load_gesture_lib(&gesture_info.gesture_lib);//加载手势库

4. ez_server_socket_id = eztune_setup_server("127.0.0.1", "55555");

if (pipe(ez_cmd_pipe)

ez_prev_server_socket_id = eztune_setup_server("127.0.0.1", "55556");

if(pipe(ez_prev_cmd_pipe)

//创建两个socket端口，同时建立两个pipe文件对两个端口进行监控

5. if (get_mctl_node_info(server_fd, &mctl_node_info))//通过服务节点获取服务的相关信息

{

//此处获取的是内核中调用msm_sensor_register()注册的sensor节点信息

}

6. sub.type = V4L2_EVENT_ALL;

rc = ioctl(server_fd, VIDIOC_SUBSCRIBE_EVENT, &sub);//通过服务设备文件的ioctl接口，订阅所有的事件

7. config_arg.server_fd = server_fd;

config_arg.ez_read_fd = ez_cmd_pipe[0];

config_arg.ez_write_fd = ez_cmd_pipe[1];

config_arg.ez_prev_read_fd = ez_prev_cmd_pipe[0];

config_arg.ez_prev_write_fd = ez_prev_cmd_pipe[1];//初始化配置线程的参数

8.下面就是一个循环，对这几个文件进行poll

do {

fds[0].fd = server_fd;

fds[0].events = POLLPRI;

fds[1].fd = ez_server_socket_id;

fds[1].events = POLLIN;

fds[2].fd = ez_prev_server_socket_id;

fds[2].events = POLLIN;

rc = poll(fds, 3, timeoutms);

if (fds[0].revents & POLLPRI) { /* Server Node Wake Up *

//对服务的设备文件进行监视，当遇到打开事件的时候，立即创建一个配置线程

rc = qcamsvr_process_server_node_event(&config_arg, &mctl_node_info,

&gesture_info);

}

//线面就是对两个socket进程监视和处理。

if ((fds[1].revents & POLLIN) == POLLIN) { /* EzTune Server */

int client_socket_id;

client_socket_id = accept(ez_server_socket_id,

(struct sockaddr *)&addr_client_inet, &addr_client_len);

write(ez_cmd_pipe[1], &client_socket_id, sizeof(int));

}

}

if ((fds[2].revents & POLLIN) == POLLIN) { /* EzTune Prev Server */

int client_socket_id;

client_socket_id = accept(ez_prev_server_socket_id,

(struct sockaddr *)&addr_client_inet, &addr_client_len);

write(ez_prev_cmd_pipe[1], &client_socket_id, sizeof(int));

}

}

} /* Else for Poll rc */

} while (1);

}

下面进入配置线程创建的流程：

//取出服务节点产生的事件，然后根据配置节点的名称，分发给各自独立的主控制线程

1. static int qcamsvr_process_server_node_event()

{

//下命令让服务模块的事件出队列进行处理

rc = ioctl(config_arg->server_fd, VIDIOC_DQEVENT, &v4l2_evt);

if (v4l2_evt.type == V4L2_EVENT_PRIVATE_START + MSM_GES_RESP_V4L2)

{

//如果是手势事件，则进行一系列的处理

if (ctrl->type == MSM_V4L2_GES_OPEN) {

//设置主控线程的接口

p_gesture_info->cam_mctl.svr_ops.launch_mctl_thread =

create_v4l2_conf_thread;

//设置主控线程的退出接口

p_gesture_info->cam_mctl.svr_ops.release_mctl_thread =

destroy_v4l2_cam_conf_thread;

//设置camera使能

p_gesture_info->cam_mctl.svr_ops.camera_available =

qcamsvr_camera_available;

//设置服务设备文件的文件句柄

p_gesture_info->cam_mctl.svr_ops.server_fd = config_arg->server_fd;

//创建手势服务

status = p_gesture_info->gesture_lib.gesture_service_create(

&p_gesture_info->cam_mctl, &p_gesture_info->observer);

}

else if (ctrl->type == MSM_V4L2_GES_CLOSE) {

//消亡手势服务

status = p_gesture_info->gesture_lib.gesture_service_send_data(ctrl)

}

if ((status == CAMERA_SUCCESS) &&

(ctrl->type != MSM_V4L2_GES_CLOSE)) {

//如果成功，且文件打开，则向手势服务发送数据

status = p_gesture_info->gesture_lib.gesture_service_send_data(ctrl);

if (status != CAMERA_SUCCESS) {

LOGE("gesture_service_send_data failed");

}

} else {

if (ctrl->type == MSM_V4L2_GES_CLOSE) {

ctrl->status = CAM_CTRL_SUCCESS;

} else {

LOGE("gesture send failure message");

ctrl->status = CAM_CTRL_FAILED;

}

//将操作结果反馈给camera服务

v4l2_ioctl.ioctl_ptr = ctrl;

qcamsvr_send_ctrl_cmd_done(config_arg->server_fd, &v4l2_ioctl);

//如果是camera事件，则进行一系列的处理

}

else if (v4l2_evt.type == V4L2_EVENT_PRIVATE_START + MSM_CAM_RESP_V4L2)

{

if (ctrl->type == MSM_V4L2_OPEN) {

//通过pipe进行一些初始化工作

//创建一个核心的线程

if ((tmp_mctl_struct->handle =

//反馈结果给camera服务端

ctrl->status = CAM_CTRL_SUCCESS;

v4l2_ioctl.ioctl_ptr = ctrl;

qcamsvr_send_ctrl_cmd_done(config_arg->server_fd, &v4l2_ioctl);

}

else if (ctrl->type == MSM_V4L2_CLOSE){

//进行一些消亡工作

//通过写一些pipe

if (destroy_v4l2_cam_conf_thread(tmp_mctl_struct->handle) < 0) //消亡只线程

ctrl->status = CAM_CTRL_SUCCESS;

v4l2_ioctl.ioctl_ptr = ctrl;

//反馈结果给camera服务

qcamsvr_send_ctrl_cmd_done(config_arg->server_fd, &v4l2_ioctl);

}

else {

//通过pipe写一些命令，等待配置返回

}

}

//首先来看一下刚刚的线程创建函数

void *create_v4l2_conf_thread(struct config_thread_arguments* arg)

{

//核心工作就是创建了个线程

rc = pthread_create(&pme->cam_mctl_thread_id, NULL, cam_mctl_thread, pme);

}

//下面进入创建的配置线程的主函数：

static void *cam_mctl_thread(void *data)(mctl.c)

{

//首先初始化需要监控的文件句柄

pipe_readfd = arg->read_fd;

pipe_writefd = arg->write_fd;

server_fd = arg->server_fd;

ez_pipe_readfd = arg->ez_read_fd;

ez_client_fd = -1;

ez_prev_pipe_readfd = arg->ez_prev_read_fd;

ez_prev_client_fd = -1;

//向对应的配置节点下命令监控所有事件(此文件句柄具体标识什么意思暂时还没搞清楚)

sub.type = V4L2_EVENT_ALL;

rc = ioctl(cam_fd, VIDIOC_SUBSCRIBE_EVENT, &sub);

//下面开始进入循环的监控

do {

//文件句柄初始化

fds[0].fd = cam_fd;

fds[0].events = POLLPRI;

fds[1].fd = pipe_readfd;

fds[1].events = POLLPRI | POLLIN;

fds[2].fd = ez_pipe_readfd;

fds[2].events = POLLIN;

fds[3].fd = ez_client_fd;

fds[3].events = POLLIN;

fds[4].fd = ez_prev_pipe_readfd;

fds[4].events = POLLIN;

fds[5].fd = ez_prev_client_fd;

fds[5].events = POLLIN;

/* evt/msg from qcam server */

if (ctrl->type == MSM_V4L2_CLOSE) {

//关闭所有的资源

config_shutdown_pp(pme->p_cfg_ctrl);

//反馈结果给服务

rc = mctl_send_ctrl_cmd_done(pme->p_cfg_ctrl, NULL, TRUE);

}

else {

//此函数为用户控件的APP处理对应的命令

if (mctl_proc_v4l2_request(pme, ctrl) < 0)

}

/* evt/msg from config node */

rc = ioctl(cam_fd, VIDIOC_DQEVENT, &v4l2_event);//下事件出队列的命令

if (v4l2_event.type ==

V4L2_EVENT_PRIVATE_START + MSM_CAM_RESP_DIV_FRAME_EVT_MSG) {

//进程对应的帧转移

mctl_pp_divert_frame(p_cfg_ctrl,

(void *)&(event_data.isp_data.div_frame));

}else if(v4l2_event.type ==

V4L2_EVENT_PRIVATE_START + MSM_CAM_RESP_MCTL_PP_EVENT) {

//处理后置的事件

mctl_pp_proc_event(p_cfg_ctrl,

(void *)&(event_data.isp_data.pp_event_info));

}

else if (v4l2_event.type ==

V4L2_EVENT_PRIVATE_START + MSM_CAM_RESP_STAT_EVT_MSG) {

//处理正常的事件消息

mctl_proc_event_message (pme, isp_adsp);

}

else {

CDBG_HIGH("%s: Error: should not be here", __func__);

}

/* evt/msg from eztune pipe */

if (ez_client_fd > 0)

mctl_eztune_server_connect(pme, ez_client_fd);

/* evt/msg from eztune client */

if (ez_client_fd > 0) {

mctl_eztune_read_and_proc_cmd(EZ_MCTL_SOCKET_CMD);

/* evt/msg from eztune prev pipe */

if (ez_prev_client_fd > 0)

mctl_eztune_prev_server_connect(pme, ez_prev_client_fd);

}

/* evt/msg from eztune prev client */

if ((fds[5].revents & POLLIN) == POLLIN) {

if (ez_prev_client_fd > 0) {

mctl_eztune_read_and_proc_cmd(EZ_MCTL_PREV_SOCKET_CMD);

}

}

}wile(TRUE)

//循环结束取消订阅所有消息

if (ioctl(cam_fd, VIDIOC_UNSUBSCRIBE_EVENT, &sub) < 0)

}

先来看看camera在硬件抽象层的接口：

主要是三点：

1. preview：预览

2. recording 录像

3. picture 拍照

模块接口函数：

get_number_of_cameras: get_number_of_cameras,

get_camera_info: get_camera_info,

camera_info_t：

typedef struct {

int modes_supported;//支持的模式

int8_t camera_id;//id标识

cam_position_t position;//前摄还是后摄

uint32_t sensor_mount_angle;//角度

}camera_info_t;

我们目前使用的高通8X平台：

Camera模块：

此模块有一个全局的camera服务结构体实例，用于全局管理各种子系统设备。

子系统设备常见的有：

enum msm_cam_subdev_type {

CSIPHY_DEV,

CSID_DEV,

CSIC_DEV,

ISPIF_DEV,

VFE_DEV,

AXI_DEV,

VPE_DEV,

SENSOR_DEV,

ACTUATOR_DEV,

EEPROM_DEV,

GESTURE_DEV,

};

定义一个抽象的camera服务设备：

struct msm_cam_server_dev {

/* config node device*/

struct platform_device *server_pdev;

/* server node v4l2 device */

struct v4l2_device v4l2_dev;

struct video_device *video_dev;

struct media_device media_dev;

/* info of sensors successfully probed*/

struct msm_camera_info camera_info;

/* info of configs successfully created*/

struct msm_cam_config_dev_info config_info;

/* active working camera device - only one allowed at this time*/

struct msm_cam_v4l2_device *pcam_active;

/* number of camera devices opened*/

atomic_t number_pcam_active;

struct v4l2_queue_util server_command_queue;

/* This queue used by the config thread to send responses back to the

* control thread. It is accessed only from a process context.

*/

struct msm_cam_server_queue server_queue[MAX_NUM_ACTIVE_CAMERA];

uint32_t server_evt_id;

struct msm_cam_server_mctl_inst mctl[MAX_NUM_ACTIVE_CAMERA];

uint32_t mctl_handle_cnt;

int use_count;

/* all the registered ISP subdevice*/

struct msm_isp_ops *isp_subdev[MSM_MAX_CAMERA_CONFIGS];

/* info of MCTL nodes successfully probed*/

struct msm_mctl_node_info mctl_node_info;

struct mutex server_lock;

struct mutex server_queue_lock;

/*v4l2 subdevs*/

struct v4l2_subdev *csiphy_device[MAX_NUM_CSIPHY_DEV];

struct v4l2_subdev *csid_device[MAX_NUM_CSID_DEV];

struct v4l2_subdev *csic_device[MAX_NUM_CSIC_DEV];

struct v4l2_subdev *ispif_device;

struct v4l2_subdev *vfe_device[MAX_NUM_VFE_DEV];

struct v4l2_subdev *axi_device[MAX_NUM_AXI_DEV];

struct v4l2_subdev *vpe_device[MAX_NUM_VPE_DEV];

struct v4l2_subdev *gesture_device;

};

从控制流的角度来分析下camera的流程。

首先camera会启动一个daemon进程来进行核心的操作。

启动daemon进程的地方：

在init.target.rc文件中

#start camera server as daemon

service qcamerasvr /system/bin/mm-qcamera-daemon

class late_start

user system

group system camera inet

生成此mm-qcamera-daemon bin档的地方：

android\vendor\qcom\proprietary\mm-camera\apps\appslib\Android.mk

此mk文件生成了mm-qcamera-daemon bin档

Daemon进程的入口函数：mian()(camdaemon.c)

抽象层到内核层的大致流程：

抽象层主要通过server node和config node将command下到内核，对应的节点驱动将command通过事件队列进行管理。

而daemon进程通过开启对应的线程，不停的对事件队列进行轮询，处理上层下的command

在main daemon thread中重要的任务：

一：将sensor操作关联的硬件组件加载进来，还要加载一些必备的库，为camera的正式工作铺垫环境：

① AXI_comp_create

② sensor_comp_create

③ flash_led_comp_create

④ flash_strobe_comp_create

⑤ CAMIF_comp_create

⑥ VFE_comp_create

⑦ ACTUATOR_comp_create

⑧ eeprom_comp_create

⑨ mctl_load_stats_proc_lib

⑩ mctl_load_frame_proc_lib

二．线程的循环工作

线程，顾名思义，肯定有一个封闭的循环体，在循环体中做一些核心的操作

而Daemon进程的主线程轮询服务节点的event queue，获取事件，纷发给各自的mctl thread

Daemon进行的主线程主要处理一下基类事件“

① MSM_GES_RESP_V4L2 ：

Open:主要进行初始化，铺垫环境，开启处理camera细节活动的线程

Close：进行一些善后工作

② MSM_CAM_RESP_V4L2：处理open和colse

Open:主要进行初始化，铺垫环境，开启处理camera细节活动的线程

Close：进行一些善后工作

③ 其他一些事件都是通过pipe通信直接写入到①②两点创建的线程中（send command through pipe and wait for config to return）

在mctl thread中重要的任务：

一. 打开confing节点文件

二. 调用create_camfd_receive_socket猜测是与硬件抽象层进行直接通信的

三. 创建mctl_pp_poll_thread线程，

四. 初始化camera的几个feature:

①zoom_init_ctrl

②bestshot_init

③hdr_init

五.通过pipe通信获取server节点的控制事件，事件由Daemon进程的主控线程获取并且通过pipe传递过来

六．通过监测config节点的事件获取config节点对应的控制command

主要监测三类事件：

① MSM_CAM_RESP_DIV_FRAME_EVT_MSG

② MSM_CAM_RESP_MCTL_PP_EVENT

③ MSM_CAM_RESP_STAT_EVT_MSG

将这三个事件以command的形式，通过pipe通信发送到(一)中创建的PP线程中

在mctl_pp_poll_thread中重要的任务：

一：对几个pipe文件进行监测，与其他线程进行交互

几种事件：

①/* Events on pipe between mctl thread - mctl pp thread */

②/* Events on user created socket */

③/* Events on mctl pp node */

④/* Events on pipe between mctl pp thread and c2d thread */

Qualcomm 8X camera daemon进程浅析