camera daemon进程

一、守护进程启动包含的路径文件

1) 确定daemon进程编译路径

代码路径：vendor/qcom/proprietary/mm-camera/Android.mk

概述：确定生成mm-qcamera-daemon的路径

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BUILD_SERVER := false

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BUILD_SERVER_BOARD_PLATFORM_LIST := msm7627a

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm7630_surf

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm7630_fusion

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BUILD_SERVER_BOARD_PLATFORM_LIST += msm8660

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm8960

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm8974

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm8226

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#BUILD_SERVER_BOARD_PLATFORM_LIST += msm8610

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ifeq ($(call is-board-platform-in-list,$(BUILD_SERVER_BOARD_PLATFORM_LIST)),true)

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  BUILD_SERVER := true

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  USE_SERVER_TREE := -D_V4L2_BASED_CAM_

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endif

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​

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BUILD_MM_CAMERA2 := false

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST := msm8960

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST += msm8974

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST += msm8226

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST += msm8610

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST += msm8916

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BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST += msm8909

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ifeq ($(call is-board-platform-in-list,$(BUILD_MM_CAMERA2_BOARD_PLATFORM_LIST)),true)

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  BUILD_MM_CAMERA2 := true

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endif

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​

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/***由此可以得知BUILD_SERVER=flase BUILD_MM_CAMERA2 =true ***/

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​

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  ifeq ($(BUILD_SERVER), true)

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    include $(MY_PATH)/apps/Android.mk

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    include $(MY_PATH)/server/Android.mk

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  else ifeq ($(BUILD_MM_CAMERA2), true)

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    include $(MY_PATH)/mm-camera2/Android.mk/***包含的路径是vendor/qcom/proprietary/mm-camera/mm-camera2/Android.mk***/

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  else

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    include $(MY_PATH)/apps/Android.mk

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    include $(MY_PATH)/targets/Android.mk

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  endif

代码路径：vendor/qcom/proprietary/mm-camera/mm-camera2/server-imaging/Android.mk

概述：确定生成 mm-qcamera-daemon的包含的文件

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LOCAL_MODULE:= mm-qcamera-daemon    LOCAL_MODULE模块必须定义，以表示Android.mk中的每一个模块。名字必须唯一且不包含空格。

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LOCAL_SRC_FILES:= server.c  server_process.c

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​

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LOCAL_C_INCLUDES:=$(LOCAL_PATH)/******可以知道守护进程处理的文件路径范围******/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../includes/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/bus/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/controller/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/object/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/includes/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/tools/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/event/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/pipeline/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/stream/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/module/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/port/

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LOCAL_C_INCLUDES+= $(LOCAL_PATH)/../media-controller/mct/debug/

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​

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​

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LOCAL_SHARED_LIBRARIES:= libcutils libdl liboemcamera \   /***库文件路径：out\target\product\msm8909\system\vendor\lib\libmmcamera2_stats_modules.so

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                                   libmmcamera2_stats_modules \

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                                   libmmcamera2_iface_modules \

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                                   libmmcamera2_isp_modules \

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                                   libmmcamera2_sensor_modules \

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                                   libmmcamera2_pproc_modules \

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                                   libmmcamera2_imglib_modules

代码路径：device/qcom/msm8909/init.target.rc

概述：启动mm-qcamera-daemon服务

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#start camera server as daemon

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

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    class late_start

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    user camera

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    group camera system inet input graphics

代码路径：device/qcom/common/rootdir/etc/init.qcom.rc

概述：为域套接字的通信创建文件

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#Create folder for mm-qcamera-daemon

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    mkdir /data/camera 0770 media camera

二、守护进程具体的内容

1) 初始化模块

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int main(int argc, char *argv[])

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{

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  mct_list_t                *listen_fd_list = NULL;

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  read_fd_info_t            *hal_fd = NULL, *hal_ds_fd = NULL, *mct_fds = NULL;

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  server_select_fds_t       select_fds;

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  struct v4l2_event         event;

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  /* 1. find server node name and open the node */

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  get_server_node_name(serv_hal_node_name;

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  hal_fd->fd[0] = open(dev_name, O_RDWR | O_NONBLOCK);/****dev_name = dev/video0***/

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  hal_fd->type = RD_FD_HAL;

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  listen_fd_list = mct_list_append(listen_fd_list, hal_fd, NULL, NULL);/******/

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  property_get("cameradaemon.SaveMemAtBoot", savemem, "0");

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  enabled_savemem = atoi(savemem);

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  /* 2. after open node, initialize modules */

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  server_process_module_sensor_init();

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  /***

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  *server_process_module_sensor_init只是初始化了modules_list[0].init_mod(modules_list[0].name);即sensor

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  ***/

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  if (enabled_savemem != 1) {

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    if (server_process_module_init() == FALSE);

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     /***

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     *for (i = 1; i < (int)(sizeof(modules_list)/sizeof(mct_module_init_name_t)); i++)

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     *所以会初始化iface、isp、stats、pproc、imglib这五个模块

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     ***/

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    }

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   /* Subcribe V4L2 event */

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  subscribe.type = MSM_CAMERA_V4L2_EVENT_TYPE;

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  ioctl(hal_fd->fd[0], VIDIOC_SUBSCRIBE_EVENT, &subscribe);/***函数分析1、2***/

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  select_fds.select_fd = hal_fd->fd[0];

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  CDBG("CAMERA_DAEMON:waiting for camera to open\n");

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  do {

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       FD_ZERO(&(select_fds.fds));

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       mct_list_traverse(listen_fd_list, server_reset_select_fd, &select_fds); /***函数分析3***/

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       ret = select(select_fds.select_fd + 1, &(select_fds.fds), NULL, NULL, NULL);  

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       if (ret > 0)

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        {

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           mct_list_t     *find_list;

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           read_fd_info_t *fd_info;

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           find_list = mct_list_find_custom(listen_fd_list, &(select_fds.fds), server_check_listen_fd);

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            /***通过select_fds.fds中被置1的fd找到对应的链表***/

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           fd_info = (read_fd_info_t *)find_list->data;

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           switch (fd_info->type) {

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           case RD_FD_HAL: {

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             if (ioctl(fd_info->fd[0], VIDIOC_DQEVENT, &event) < 0)

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                continue;

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           /* server process HAL event:

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            *   1. if it returns success, it means the event message has been posted to MCT, don't need to send CMD ACK back to kernel

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            *      immediately, because MCT will notify us after process;

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            *

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            *   2. if it returns failure, it means the event message was not posted to MCT successfully, hence we need to send CMD ACK back

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            *      to kernel immediately so that HAL thread which sends this event can be blocked.

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            */

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              proc_ret = server_process_hal_event(&event);

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            break;

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          case RD_DS_FD_HAL:

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          /* server process message sent by HAL through Domain Socket */

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              proc_ret = server_process_hal_ds_packet(fd_info->fd[0],fd_info->session);

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            break;

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          case RD_PIPE_FD_MCT:

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          /* server process message sent by media controller through pipe: */

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            proc_ret = server_process_mct_msg(fd_info->fd[0],  fd_info->session);

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            break;

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          default:

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             continue;

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        } /* switch (fd_info->type) */    

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    }while (1);

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}

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函数分析：

1) 代码路径：vendor/qcom/proprietary/mm-camera/mm-camera2/server-imaging/server_process.c

函数：server_process_module_init();

概述：对modules_list数组中的模块进行初始化

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static mct_module_init_name_t modules_list[] = {

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  {"sensor", module_sensor_init,   module_sensor_deinit, NULL},

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  {"iface",  module_iface_init,   module_iface_deinit, NULL},

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  {"isp",    module_isp_init,      module_isp_deinit, NULL},

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  {"stats",  stats_module_init,    stats_module_deinit, NULL},

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  {"pproc",  pproc_module_init,    pproc_module_deinit, NULL},

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  {"imglib", module_imglib_init, module_imglib_deinit, NULL},

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};

2) 代码路径：kernel/drivers/media/platform/msm/camera_v2/camera/camera.c

函数：int camera_init_v4l2(struct device *dev, unsigned int *session);

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int camera_init_v4l2(struct device *dev, unsigned int *session)

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{

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    struct msm_video_device *pvdev;

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    struct v4l2_device *v4l2_dev;

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    pvdev->vdev->release  = video_device_release;

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    pvdev->vdev->fops     = &camera_v4l2_fops;

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    pvdev->vdev->ioctl_ops = &camera_v4l2_ioctl_ops;

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    pvdev->vdev->minor     = -1;

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    pvdev->vdev->vfl_type  = VFL_TYPE_GRABBER;

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    rc = video_register_device(pvdev->vdev, VFL_TYPE_GRABBER, -1);

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}

函数ioctl(hal_fd->fd[0], VIDIOC_SUBSCRIBE_EVENT, &subscribe);打开的文件是dev/video0，所以ioctl调用是这video_register_device注册的ioctl_ops。

这里主要关注的两个函是

函数：static unsigned int  camera_v4l2_poll(struct file *filep,   struct poll_table_struct *wait)

作用：select函数通过设备文件的poll函数来检查是否可读、可写。（用户空间的select系统调用对应内核中的poll函数）

参考文章： http://blog.csdn.net/waldmer/article/details/18735517  关于select的调用方法

                   http://blog.csdn.net/gtkknd/article/details/7229576   关于返回值的解析

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static unsigned int camera_v4l2_poll(struct file *filep,   struct poll_table_struct *wait)

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{

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    int rc = 0;

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    struct camera_v4l2_private *sp = fh_to_private(filep->private_data);

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    if (sp->is_vb2_valid == 1)

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        rc = vb2_poll(&sp->vb2_q, filep, wait);

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​

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    poll_wait(filep, &sp->fh.wait, wait);

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    if (v4l2_event_pending(&sp->fh))

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        rc |= POLLPRI;

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    return rc;

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}

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​

在函数camera_v4l2_poll(）中的v4l2_event_pending()函数返回的是fh->navailable;

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int v4l2_event_pending(struct v4l2_fh *fh)

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{

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    return fh->navailable;

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}

函数：static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,  const struct timespec *ts)

作用： fh->sequence++;

函数：static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)

作用： fh->sequence--;

例如MSM_CAMERA_NEW_SESSION的过程

HAL层：调用int32_t mm_camera_open(mm_camera_obj_t *my_obj)打开camera

kernel层：static int camera_v4l2_open(struct file *filep)  ---->  camera_pack_event(filep, MSM_CAMERA_NEW_SESSION, 0, -1, &event);---->  

                  rc = msm_post_event(&event, MSM_POST_EVT_TIMEOUT);---->  v4l2_event_queue(vdev, event);----> __v4l2_event_queue_fh(fh, ev, &timestamp);

                  ----> fh->sequence++; ---> static unsigned int camera_v4l2_poll(struct file *filep,  struct poll_table_struct *wait) ---> rc |= POLLPRI; （ POLLPRI表示 可读 ）

vendor层：ret = select(select_fds.select_fd + 1, &(select_fds.fds), NULL, NULL, NULL)---> ioctl(fd_info->fd[0], VIDIOC_DQEVENT, &event)---> fh->sequence--;

                   通过select系统调用获得kernel的fd的状态改变，从而进行事件的处理,同时调用 VIDIOC_DQEVENT使得fh->sequence--。

3)代码路径：vendor/qcom/proprietary/mm-camera/mm-camera2/media-controller/mct/tools/mct_list.c

函数：boolean mct_list_traverse(mct_list_t *mct_list, mct_list_traverse_func traverse,  void *user_data);

函数：mct_list_traverse(listen_fd_list, server_reset_select_fd, &select_fds);

作用：Traverse whole list

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boolean mct_list_traverse(mct_list_t *mct_list, mct_list_traverse_func traverse, void *user_data)

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{

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  mct_list_t *temp_list;

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  uint32_t num;

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​

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  if (mct_list && traverse) {

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    if (traverse(mct_list->data, user_data) == FALSE)

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      return FALSE;

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​

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    num = mct_list->next_num;

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    if (num > 0 && mct_list->next) {

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      temp_list = mct_list->next[0];

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      while (num--) {

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        mct_list_traverse(temp_list, traverse, user_data);/***递归地遍历执行traverse(mct_list->data, user_data)函数***/

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        temp_list++;

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      }

17

    }

18

  }

19

​

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  return TRUE;

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}

函数：static boolean server_reset_select_fd(void *data, void *user_data)

作用：

1

static boolean server_reset_select_fd(void *data, void *user_data)

2

{

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  read_fd_info_t      *fd_info  = (read_fd_info_t *)data;

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  server_select_fds_t *selected = (server_select_fds_t *)user_data;

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  FD_SET(fd_info->fd[0], &(selected->fds)); /***FD_SET(int fd, fd_set *fdset);  将fd加入set集合***/

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  selected->select_fd = MTYPE_MAX(selected->select_fd, fd_info->fd[0]);/***FD_SET(int fd, fd_set *fdset);  将fd加入set集合***/

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​

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  return TRUE;

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}

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​

Camera daemon handles the following types of domain socket messages:

    域套接字

  消息类型：

   Buffer mapping –Handled via type RD_DS_FD_HAL 对应于  hal_ds_fd->fd[0]

   消息来源：     

      hal_ds_fd->session = proc_ret.new_session_info.session_idx;

      hal_ds_fd->fd[0] = proc_ret.new_session_info.hal_ds_fd;/***域套接字***/

      hal_ds_fd->type = RD_DS_FD_HAL;

   VIDIOC_SUBSCRIBE_EVENT

   消息类型：

       Video node updates from kernel –Handled via type RD_FD_HAL 对应于 hal_fd->fd[0]

   消息来源：

        hal_fd->fd[0] = open(dev_name, O_RDWR | O_NONBLOCK); /****dev_name = dev/video0***/

        hal_fd->type = RD_FD_HAL;

       ioctl(hal_fd->fd[0], VIDIOC_SUBSCRIBE_EVENT, &subscribe)

   管道

   消息类型：

      Updates from MCT (over Unix pipe) –Handled via type RD_PIPE_FD_MCT  对应于 mct_fds->fd[0]

   消息来源：

      mct_fds->session = proc_ret.new_session_info.session_idx;

      mct_fds->fd[0] = proc_ret.new_session_info.mct_msg_rd_fd;/***管道***/

      mct_fds->fd[1] = proc_ret.new_session_info.mct_msg_wt_fd;/***管道***/

      mct_fds->type = RD_PIPE_FD_MCT;

通过下面三个函数将三个不同类型的fd全部添加到 listen_fd_list这个链表中，最后通过mct_list_traverse(listen_fd_list, server_reset_select_fd, &select_fds);获取最大的 fd作为select函数的第一个参数。

listen_fd_list = mct_list_append(listen_fd_list,hal_ds_fd, NULL, NULL)

|---> mct_list_t* mct_list_append(mct_list_t *mct_list, void *data, void *appendto, mct_list_find_func list_find)

      |---> new_list = mct_list_new(data);

listen_fd_list = mct_list_append(listen_fd_list, mct_fds, NULL, NULL)

|---> mct_list_t* mct_list_append(mct_list_t *mct_list, void *data, void *appendto, mct_list_find_func list_find)

      |---> new_list = mct_list_new(data);

listen_fd_list = mct_list_append(listen_fd_list, hal_fd, NULL, NULL)

|---> mct_list_t* mct_list_append(mct_list_t *mct_list, void *data, void *appendto, mct_list_find_func list_find)

      |---> new_list = mct_list_new(data);

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