android 为摄像头增加闪光灯(s5pv210)

偏执的太偏执、 2022-06-10 11:45 563阅读 0赞

昨天刚好闪光灯弄过来，今天简单的做下总结。大概的说下，具体我也没有深入研究，不过效果确实是有了。

首先找到android拍照的时候所执行的函数代码在：

packages/apps/Camera/src/com/android/camera/Camera.java

找到这个地方：

mCameraDevice.setParameters(mParameters);
                mCameraDevice.takePicture(mShutterCallback, mRawPictureCallback,
                        mPostViewPictureCallback, new JpegPictureCallback(loc));
                mPreviewing = false;

据我理解，这里就是拍照的时候所执行的，而这里应该是调用的camera库里的takepicture下面我们找到库文件：

device/samsung/proprietary/libcamera

库文件就在这里，下面我们进入SeccameraHWInterface.cpp文件查找takepicture如下:

status_t CameraHardwareSec::takePicture()
    {
        LOGV("%s :", __func__);
    
        stopPreview();
    
        Mutex::Autolock lock(mStateLock);
        if (mCaptureInProgress) {
            LOGE("%s : capture already in progress", __func__);
            return INVALID_OPERATION;
        }
    
        if (mPictureThread->run("CameraPictureThread", PRIORITY_DEFAULT) != NO_ERROR) {
            LOGE("%s : couldn't run picture thread", __func__);
            return INVALID_OPERATION;
        }
        mCaptureInProgress = true;
    
        return NO_ERROR;
    }

里面的mPictureThread->run就是拍照的东西了，具体我就不分析了。接下来我们找下闪光灯的接口

在SecCamera.h里你会发现下面三个函数接口：

bool            getFlashSupport(void);
        int             setFlashMode(int flash_mode);
        int             getFlashMode(void);

其中setFlashMode即为设置闪光灯的接口，找到这个函数

在SecCamera.cpp里如下:

int SecCamera::setFlashMode(int flash_mode)
    {
        LOGV("%s(flash_mode(%d))", __func__, flash_mode);
    
        if (flash_mode <= FLASH_MODE_BASE || FLASH_MODE_MAX <= flash_mode) {
            LOGE("ERR(%s):Invalid flash_mode (%d)", __func__, flash_mode);
            return -1;
        }
    
        if (m_params->flash_mode != flash_mode) {
            m_params->flash_mode = flash_mode;
            if (m_flag_camera_start) {
                if (fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode) < 0) {
                    LOGE("ERR(%s):Fail on V4L2_CID_CAMERA_FLASH_MODE", __func__);
                    return -1;
                }
            }
        }
        return 0;
    }

这里又会调用fimc\_v4l2\_s\_ctrl函数代码如下:

static int fimc_v4l2_s_ctrl(int fp, unsigned int id, unsigned int value)
    {
        struct v4l2_control ctrl;
        int ret;
    
        ctrl.id = id;
        ctrl.value = value;
        //LOGD("%s :--------------------------value is %d",__func__,value);//add dao
        ret = ioctl(fp, VIDIOC_S_CTRL, &ctrl);
        if (ret < 0) {
            LOGE("ERR(%s):VIDIOC_S_CTRL(id = %#x (%d), value = %d) failed ret = %d\n",
                 __func__, id, id-V4L2_CID_PRIVATE_BASE, value, ret);
    
            return ret;
        }
    
        return ctrl.value;
    }

在这里进行了ioctl下面我们到内核里面去看看。  
在内核下面的drivers/media/video/ v4l2-ioctl.c有如下代码:

case VIDIOC_S_CTRL:
    	{
    		struct v4l2_control *p = arg;
    		struct v4l2_ext_controls ctrls;
    		struct v4l2_ext_control ctrl;
    
    		if (!ops->vidioc_s_ctrl && !ops->vidioc_s_ext_ctrls)
    			break;
    
    		dbgarg(cmd, "id=0x%x, value=%d\n", p->id, p->value);
    
    		if (ops->vidioc_s_ctrl) {
    			ret = ops->vidioc_s_ctrl(file, fh, p);
    			break;
    		}
    		if (!ops->vidioc_s_ext_ctrls)
    			break;
    
    		ctrls.ctrl_class = V4L2_CTRL_ID2CLASS(p->id);
    		ctrls.count = 1;
    		ctrls.controls = &ctrl;
    		ctrl.id = p->id;
    		ctrl.value = p->value;
    		if (check_ext_ctrls(&ctrls, 1))
    			ret = ops->vidioc_s_ext_ctrls(file, fh, &ctrls);
    		break;
    	}

很快我就想到了摄像头驱动里有这样的设置:

代码在drivers/media/video/samsung/ficm/ov2640.c

static const struct v4l2_subdev_core_ops ov2640_core_ops = {
    	.init = ov2640_init,	/* initializing API */
    	.s_config = ov2640_s_config,	/* Fetch platform data */
    	.queryctrl = ov2640_queryctrl,
    	.querymenu = ov2640_querymenu,
    	.g_ctrl = ov2640_g_ctrl,
    	.s_ctrl = ov2640_s_ctrl,
    };

这里有一个s\_ctrl，事实证明确实是执行了ov2640\_s\_ctrl至于怎么调用过来的没有深入研究。

下面我们看到这个函数开始的部分

static int ov2640_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
    {
    	struct i2c_client *client = v4l2_get_subdevdata(sd);
    	struct ov2640_state *state = to_state(sd);
    	int err = 0;
    	int value = ctrl->value;
    	
    	switch (ctrl->id) {
    
    	case V4L2_CID_CAMERA_FLASH_MODE:
    	case V4L2_CID_CAMERA_BRIGHTNESS:
    		break;

第一个就是闪光灯的选项，文件系统里面设置闪光灯的就是传入的这个，可没作任何处理就直接跳出了。下面我在增加闪光灯驱动：

static int flash_ctrl(int mode)
    {
    	int err;
    
    	err = gpio_request(S5PV210_GPD0(2), "GPD0"); //power
    	if (err) {
    		printk(KERN_ERR "failed to request GPD0 for "
    				"flashlight power control\n");
    		return err;
    	}
    	gpio_direction_output(S5PV210_GPD0(2), 1);
    
    	err = gpio_request(S5PV210_GPD0(3), "GPD0"); //mode
    	if (err) {
    		printk(KERN_ERR "failed to request GPD0 for "
    				"flashlight mode control\n");
    		return err;
    	}
    	/*
    		high is flash mode,low is torch mode
    	*/
    	switch(mode) {
    		case FLASH_MODE_ON:
    			gpio_direction_output(S5PV210_GPD0(3), 1);
    			break;
    		case FLASH_MODE_TORCH:
    			gpio_direction_output(S5PV210_GPD0(3), 0);
    			break;
    		default:
    			break;
    	}
    	mdelay(100);
    	gpio_direction_output(S5PV210_GPD0(2), 0);
    
    	gpio_free(S5PV210_GPD0(2));
    	gpio_free(S5PV210_GPD0(3));
    	return err;
    }

电路我就不发出来了，流程搞清楚了，大家就好弄了。

修改ov2640\_s\_ctrl为：

case V4L2_CID_CAMERA_FLASH_MODE:
    
    		err = flash_ctrl(value);
    		break;

只修改相关设置，其它的不变。现在接口已经全部写好，在看到文件系统里。  
在拍照之前加上闪光灯设置，这个可以在库里设置也可以在app里设置，我直接在库里设置的，路径我就不在打了，前面的相关函数已经全部给出了，如下：

status_t CameraHardwareSec::takePicture()
    {
        LOGV("%s :", __func__);
    
        stopPreview();
    
        Mutex::Autolock lock(mStateLock);
        if (mCaptureInProgress) {
            LOGE("%s : capture already in progress", __func__);
            return INVALID_OPERATION;
        }
    
        mSecCamera->setFlashMode(FLASH_MODE_ON);//add by dao
    
        if (mPictureThread->run("CameraPictureThread", PRIORITY_DEFAULT) != NO_ERROR) {
            LOGE("%s : couldn't run picture thread", __func__);
            return INVALID_OPERATION;
        }
        mCaptureInProgress = true;
    
        return NO_ERROR;
    }

在拍照之前设置FlashMode为FLASH\_MODE\_ON模式，结果发现这样不行，搞了半天终于发现问题所在，直接把setFlashMode改为如下:

int SecCamera::setFlashMode(int flash_mode)
    {
        LOGV("%s(flash_mode(%d))", __func__, flash_mode);
    
        fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode);
    /*
        if (flash_mode <= FLASH_MODE_BASE || FLASH_MODE_MAX <= flash_mode) {
            LOGE("ERR(%s):Invalid flash_mode (%d)", __func__, flash_mode);
            return -1;
        }
    
        if (m_params->flash_mode != flash_mode) {
            m_params->flash_mode = flash_mode;
            if (m_flag_camera_start) {
                if (fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode) < 0) {
                    LOGE("ERR(%s):Fail on V4L2_CID_CAMERA_FLASH_MODE", __func__);
                    return -1;
                }
            }
        }
    */
        return 0;
    }

重新编译库和内核，下载，结果测试成功。