camera拍摄视频耗电过快的问题分析

问题：【相机】33%电量开启闪光灯录制视频，大约6分钟左右，手机自动关机，再开机，电量为4%

分析过程：

开闪光灯录制视频的情况下导致掉电，手机关机。经过跟测试沟通之后，发现正常模式下录制视频的话，没有这个问题，那么我们就把问题点定位到闪光灯上了，由于闪光灯有Flash模式和Torch模式，在拍照时，我们用的是Flash模式，该模式瞬间曝光，一般电压在300mV ~ 75mV 之间，这个是跟连接的RSET有关，我们电路接的是139kΩ，那么根据公式VFB = (1.26V/ RSET) ×10.2kΩ (Flash Mode)，算出VFB=92.5mV。而Torch模式的话就只有VFB = 47mV (Torch Mode)。然后看了一下拍视频时闪光灯的亮度，跟拍照时的亮度是一样的，那么就肯定是我们拍视频的时候闪光灯的模式错误的设置为Flash模式了；

问题定位后就是代码分析了。首先分析的是驱动leds_strobe.c文件

129 ssize_t gpio_FL_Enable(void)
130 {
131     /*Enable*/
132     printk("FlashLight: %s:%d: called g_torch_mode:%d\n",__func__,__LINE__,g_torch_mode);
133     if(0 == g_torch_mode){
134         if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENM_PIN,GPIO_OUT_ONE)){PK_DBG("[constant_flashlight] enable flashlight failed!!     \n");}
135     if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENF_PIN,GPIO_OUT_ONE)){PK_DBG("[constant_flashlight] open flashlight failed!    ! \n");}
136     }else{
137         if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENM_PIN,GPIO_OUT_ONE)){PK_DBG("[constant_flashlight] set gpio failed!! \n");    }
138     }
139     return 0;
140 }
141
142 ssize_t gpio_FL_Disable(void)
143 {
144     /*Disable*/
145     printk("FlashLight: %s:%d: called g_torch_mode:%d\n",__func__,__LINE__,g_torch_mode);
146     if(0 == g_torch_mode){
147     if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENF_PIN,GPIO_OUT_ZERO)){PK_DBG("[constant_flashlight] close flashlight failed!!     \n");}
148         if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENM_PIN,GPIO_OUT_ZERO)){PK_DBG("[constant_flashlight] enable flashlight fail    ed!! \n");}
149     }else{
150         if(mt_set_gpio_out(GPIO_CAMERA_FLASH_ENM_PIN,GPIO_OUT_ZERO)){PK_DBG("[constant_flashlight] set gpio failed!! \n")    ;}
151     }
152     return 0;
153 }

然后我们再查看torch模式和flash模式是什么情况下设置的：

155 ssize_t gpio_FL_dim_duty(kal_uint8 duty)
156 {
157     if (duty == 0)
158         g_torch_mode = 1;
159     else
160         g_torch_mode = 0;
161     printk("FlashLight: %s:%d: called duty:%d\n",__func__,__LINE__,duty);
162     return 0;
163 }

170 #define FL_dim_duty gpio_FL_dim_duty

继续看看调用FL_dim_duty的地方：

201 static int constant_flashlight_ioctl(MUINT32 cmd, MUINT32 arg)
202 {
203     int i4RetValue = 0;
204     int ior_shift;
205     int iow_shift;
206     int iowr_shift;
207     ior_shift = cmd - (_IOR(FLASHLIGHT_MAGIC,0, int));
208     iow_shift = cmd - (_IOW(FLASHLIGHT_MAGIC,0, int));
209     iowr_shift = cmd - (_IOWR(FLASHLIGHT_MAGIC,0, int));
210     PK_DBG("constant_flashlight_ioctl() line=%d ior_shift=%d, iow_shift=%d iowr_shift=%d arg=%d\n",__LINE__, ior_shift, i
    ow_shift, iowr_shift, arg);
211     switch(cmd)
212     {
213         case FLASH_IOC_SET_TIME_OUT_TIME_MS:
214             PK_DBG("FLASH_IOC_SET_TIME_OUT_TIME_MS: %d\n",arg);
215             g_timeOutTimeMs=arg;
216         break;
217
218         case FLASH_IOC_SET_DUTY :
219             PK_DBG("FLASHLIGHT_DUTY: %d\n",arg);
220             FL_dim_duty(arg);
221             break;

好吧，那么就是跟到Ioctl,我们继续查看哪里有调用FLASH_IOC_SET_DUTY，搜索了一下，发现在

mediatek/platform/mt6592/hardware/mtkcam/core/featureio/drv/strobe/flashlight_drv.cpp中

284 int FlashlightDrv::setDuty(int duty)
285 {
286     DRV_DBG("setDuty() duty = %d\n",duty);
287     int err = 0;
288     if (m_fdSTROBE < 0)
289     {
290         DRV_DBG("setDuty() m_fdSTROBE < 0\n");
291         return StrobeDrv::STROBE_UNKNOWN_ERROR;
292     }
293     err = ioctl(m_fdSTROBE,FLASH_IOC_SET_DUTY,duty);
294     if (err < 0)
295     {
296         DRV_ERR("setDuty() err=%d\n", err);
297         return err;
298     }
299     m_duty = duty;
300     return err;
301 }

m_duty的值初始化时为0，SetDuty对duty 进行设置，讲duty的值传给m_duty，而getDuty则进行获取直接获取m_duty的值

1021 int FlashlightDrv::getDuty(int* duty)
1022 {
1023     DRV_DBG("getDuty()\n");
1024     int err = 0;
1025     if (m_fdSTROBE < 0)
1026     {
1027         DRV_DBG("getDuty() m_fdSTROBE < 0\n");
1028         return StrobeDrv::STROBE_UNKNOWN_ERROR;
1029     }
1030     *duty = m_duty;
1031     return err;
1032
1033 }

最后setDuty被文件mediatek /hardware/mtkcam/core/featureio/pipe/aaa/flash_mgr/flash_mgr.cpp调用：

210 void turnOnTorch()
211 {
212     int bOn;
213     int step;
214     int duty;
215     g_pStrobe->isOn(&bOn);
216     g_pStrobe->getDuty(&duty);
217     g_pStrobe->getStep(&step);
218
219     FLASH_PROJECT_PARA prjPara;
220     int aeMode;
221     aeMode = AeMgr::getInstance().getAEMode();
222     prjPara = FlashMgr::getInstance()->getFlashProjectPara(aeMode);
223     LogInfo("turnOnTorch line=%d isOn=%d",__LINE__,bOn);
224     if(bOn==0 || prjPara.engLevel.torchDuty!=duty || prjPara.engLevel.torchStep!=step)
225     {
226         LogInfo("turnOnTorch duty,step=%d %d",prjPara.engLevel.torchDuty, prjPara.engLevel.torchStep);
227         g_pStrobe->setDuty(prjPara.engLevel.torchDuty);
228         g_pStrobe->setStep(prjPara.engLevel.torchStep);
229         g_pStrobe->setTimeOutTime(0);
230         hwSetFlashOn();
231     }
232 }

其中：prjPara= FlashMgr::getInstance()->getFlashProjectPara(aeMode);调用：

297 FLASH_PROJECT_PARA&FlashMgr::getFlashProjectPara(int aeMode)
 298{
 299    NVRAM_CAMERA_STROBE_STRUCT* pNv;
 300    int err;
 301    err = nvGetBuf(pNv);
 302    if(err!=0)
 303        LogError("nvGetBuf err");
 304    //loadNvram();
 305    FLASH_PROJECT_PARA para;
 306if(m_sensorType==DUAL_CAMERA_MAIN_SENSOR)
 307     return cust_getFlashProjectPara(aeMode, pNv);
 308else
 309    return cust_getFlashProjectPara_sub(aeMode, pNv);
 310}

接着是cust_getFlashProjectPara(aeMode,pNv);代用下面文件，

mediatek/custom/out/huaqin92_wet_b2a_tdd/hal/camera/flash_tuning_custom.cpp中的

118 FLASH_PROJECT_PARA& cust_getFlashProjectPara(int aeMode, NVRAM_CAMERA_STROBE_STRUCT* nvrame)
119 {
120     static FLASH_PROJECT_PARA para;
121
122     para.dutyNum = 10;
123     para.stepNum = 1;
124
125     if(nvrame!=0)
126     {
127         XLOGD("cust_getFlashProjectPara nvrame->tuningPara[0].yTar=%d", nvrame->tuningPara[0].yTar);
128         switch(aeMode)
129         {
130             case LIB3A_AE_MODE_OFF:
131             case LIB3A_AE_MODE_AUTO:
132                 copyTuningPara(¶.tuningPara, &nvrame->tuningPara[0]);
133             break;
134             case LIB3A_AE_MODE_NIGHT:
135             case LIB3A_AE_MODE_CANDLELIGHT:
136             case LIB3A_AE_MODE_FIREWORKS:
137             case LIB3A_AE_MODE_NIGHT_PORTRAIT:
138                 copyTuningPara(¶.tuningPara, &nvrame->tuningPara[1]);
139             break;
140             case LIB3A_AE_MODE_ACTION:
141             case LIB3A_AE_MODE_SPORTS:
142             case LIB3A_AE_MODE_ISO_ANTI_SHAKE:
143                 copyTuningPara(¶.tuningPara, &nvrame->tuningPara[2]);
144             break;
145             case LIB3A_AE_MODE_PORTRAIT:
146                 copyTuningPara(¶.tuningPara, &nvrame->tuningPara[3]);
147             break;
148             default:
149                 copyTuningPara(¶.tuningPara, &nvrame->tuningPara[0]);
150             break;
151         }
152     }
153     //--------------------
154     //eng level
155     //index mode
156     //torch
157     para.engLevel.torchEngMode = ENUM_FLASH_ENG_INDEX_MODE;
158     para.engLevel.torchDuty = 0;
159     para.engLevel.torchStep = 0;

这个函数的160-162行可以看到：

160    para.engLevel.torchEngMode = ENUM_FLASH_ENG_INDEX_MODE;

161    para.engLevel.torchDuty= 1;

162    para.engLevel.torchStep = 0;

好了，所以我们的duty就被设置为1了，导致走的驱动层的Flash模式。

修改完成编译后，将libcameracustom.so 文件push到/system/lib/

reboot后就搞定了！