Camera４ MTK camera驱动结构介绍

一、概述：

　　MTK camera主要的内容在hal层，现在有hal1/hal3，当下主流的使用的是hal3，驱动主要负责sensor

电源的控制以及sensor相关寄存器的操作，MTK采用设备和驱动分离的思想，抽象出imgsensor.c来控制

sensor的上下电以及sensor具体的操作，结构图如下：

二、sensorDriver介绍：

　　Sensordriver的对上响应需求，对下控制sensor硬件行为，处理器通过I2C 接口来控制sensor的

大部分行为，sensor输出的数据传输到TG、ISP等模块处理后，ISP将数据保存到内存中之后，才可以

dump出sensor的数据，才能看到sensor的第一帧画面。这节主要介绍sensordriver的代码。

1、sensorDriver函数结构体：

（1）imgsensor_mode_struct不同模式特征的结构体：

　　这个结构体描叙了各个模式下的pclk/linelength/framelength 等：

struct imgsensor_mode_struct {kal_uint32 pclk;kal_uint32 linelength;kal_uint32 framelength;kal_uint8 startx;kal_uint8 starty;kal_uint16 grabwindow_width;kal_uint16 grabwindow_height;/* MIPIDataLowPwr2HighSpeedSettleDelayCount by different scenario */kal_uint8 mipi_data_lp2hs_settle_dc;/*  following for GetDefaultFramerateByScenario()  */kal_uint16 max_framerate;kal_uint32 mipi_pixel_rate;
};

　　对应的描叙信息如下：pclk ≈ linelength * frame_length * framerate：

static kal_uint32 set_max_framerate_by_scenario(enum MSDK_SCENARIO_ID_ENUM scenario_id, MUINT32 framerate)
{kal_uint32 frame_length;switch (scenario_id) {case MSDK_SCENARIO_ID_CAMERA_PREVIEW:frame_length = imgsensor_info.pre.pclk / framerate * 10 / imgsensor_info.pre.linelength;//计算frame_lengthspin_lock(&imgsensor_drv_lock);imgsensor.dummy_line = (frame_length > imgsensor_info.pre.framelength) ?(frame_length - imgsensor_info.pre.framelength) : 0;imgsensor.frame_length = imgsensor_info.pre.framelength + imgsensor.dummy_line;imgsensor.min_frame_length = imgsensor.frame_length;spin_unlock(&imgsensor_drv_lock);set_dummy(); //更新新的frame_lengthbreak;
}

sensor的linelength是固定的，每个模式的pclk也是不可调的，所以要调整帧率framerate，只能调整frame_length。

set_dummy使得当前帧率立刻变化为设置的帧率，如果pclk或者linelength与对应sensor setting的实际值不一致，

设置的帧率和响应的帧率会有一个偏差，画面可能出现水波纹：

（2）struct imgsensor_info_struct描叙sensor info常量的结构体：

struct imgsensor_info_struct {kal_uint32 sensor_id;                      /*record sensor id defined in Kd_imgsensor.h*/kal_uint32 checksum_value;                 /*checksum value for Camera Auto Test*/
//不同mode 的信息struct imgsensor_mode_struct pre;          /*preview scenario relative information*/struct imgsensor_mode_struct cap;          /*capture scenario relative information*/struct imgsensor_mode_struct cap1;struct imgsensor_mode_struct cap2;struct imgsensor_mode_struct normal_video; /*normal video  scenario relative information*/struct imgsensor_mode_struct hs_video;     /*high speed video scenario relative information*/struct imgsensor_mode_struct slim_video;   /*slim video for VT scenario relative information*/
//支持的功能kal_uint8  ae_shut_delay_frame;            /*shutter delay frame for AE cycle*/kal_uint8  ae_sensor_gain_delay_frame;     /*sensor gain delay frame for AE cycle*/kal_uint8  ae_ispGain_delay_frame;         /*isp gain delay frame for AE cycle*/kal_uint8  ihdr_support;                   /*1, support; 0,not support*/kal_uint8  ihdr_le_firstline;              /*1,le first ; 0, se first*/kal_uint8  sensor_mode_num;                /*support sensor mode num*/
//丢帧处理（丢掉不稳定帧的数据）kal_uint8  cap_delay_frame;                /*enter capture delay frame num*/kal_uint8  pre_delay_frame;                /*enter preview delay frame num*/kal_uint8  video_delay_frame;              /*enter video delay frame num*/kal_uint8  hs_video_delay_frame;           /*enter high speed video  delay frame num*/kal_uint8  slim_video_delay_frame;         /*enter slim video delay frame num*/kal_uint8  margin;                         /*sensor framelength & shutter margin*/kal_uint32 min_shutter;                    /*min shutter*/kal_uint32 max_frame_length;               /*max framelength by sensor register's limitation*/
//isp驱动电流，电流过大可能会射频干扰kal_uint8  isp_driving_current;            /*mclk driving current*/kal_uint8  sensor_interface_type;          /*sensor_interface_type*/kal_uint8  mipi_sensor_type;/*0,MIPI_OPHY_NCSI2; 1,MIPI_OPHY_CSI2, default is NCSI2, don't modify this para*//*don't modify this para*/kal_uint8  mipi_settle_delay_mode;/*0, high speed signal auto detect; 1, use settle delay,unit is ns, */kal_uint8  sensor_output_dataformat;       /*sensor output first pixel color*/kal_uint8  mclk;                           /*mclk value, suggest 24 or 26 for 24Mhz or 26Mhz*/kal_uint8  mipi_lane_num;                  /*mipi lane num*/kal_uint8  i2c_addr_table[5];/*record sensor support all write id addr, only supprt 4must end with 0xff*/
};

（3）struct imgsensor_struct记录sensor info变量的结构体，用于动态的保存sensor的关键信息：

struct imgsensor_struct {
//记录当前是normal, or H mirror, or V flip,or both H& Vkal_uint8  mirror;                        /*mirrorflip information*/
//记录当前处于哪种mode(init/preview/capture/video)kal_uint8  sensor_mode;                   /*record IMGSENSOR_MODE enum value*/
//记录当前的shutter值kal_uint32 shutter;                       /*current shutter*/
//记录当前的sensor gain值kal_uint16 gain;                          /*current gain*/kal_uint32 pclk;                          /*current pclk*/kal_uint32 frame_length;                  /*current framelength*/kal_uint32 line_length;                   /*current linelength*/kal_uint32 min_frame_length;              /*current min  framelength to max framerate*/
//记录当前的dummy pixel, dummy line的值kal_uint16 dummy_pixel;                   /*current dummypixel*/kal_uint16 dummy_line;                    /*current dummline*/kal_uint16 current_fps;                   /*current max fps*/kal_bool   autoflicker_en;                /*record autoflicker enable or disable*/kal_bool   test_pattern;                  /*record test pattern mode or not*/
//记录当前处于哪个scenario（ preview/capture/video）enum MSDK_SCENARIO_ID_ENUM current_scenario_id;/*current scenario id*/kal_bool   ihdr_en;                       /*ihdr enable or disable*/
//记录当前i2c使用的addresskal_uint8  i2c_write_id;                  /*record current sensor's i2c write id*/
};

2、驱动入口xxxx_MIPI_RAW_SensorInit：

　　可以看到SensorInit以函数指针的形式传入到kdSensorList结构体中：

//kernel-4.9/drivers/misc/mediatek/imgsensor/src/common/v1/imgsensor_sensor_list.c
struct IMGSENSOR_INIT_FUNC_LIST kdSensorList[MAX_NUM_OF_SUPPORT_SENSOR] = {#if defined(XXXXX_MIPI_RAW){XXXXX_SENSOR_ID,SENSOR_DRVNAME_XXXXX_MIPI_RAW,XXXXX_MIPI_RAW_SensorInit},#endif......
}UINT32 XXXXX_MIPI_RAW_SensorInit(struct SENSOR_FUNCTION_STRUCT **pfFunc)
{/* Check Sensor status here */if (pfFunc != NULL)*pfFunc = &sensor_func;return ERROR_NONE;
}

　　SENSOR_FUNCTION_STRUCT这个结构体包含了所有sensorDriver的操作接口：

struct SENSOR_FUNCTION_STRUCT {MUINT32 (*SensorOpen)(void);MUINT32 (*SensorGetInfo)(enum MSDK_SCENARIO_ID_ENUM ScenarioId,MSDK_SENSOR_INFO_STRUCT *pSensorInfo,MSDK_SENSOR_CONFIG_STRUCT *pSensorConfigData);MUINT32 (*SensorGetResolution)(MSDK_SENSOR_RESOLUTION_INFO_STRUCT * pSensorResolution);MUINT32 (*SensorFeatureControl)(MSDK_SENSOR_FEATURE_ENUM FeatureId,MUINT8 *pFeaturePara,MUINT32 *pFeatureParaLen);MUINT32 (*SensorControl)(enum MSDK_SCENARIO_ID_ENUM ScenarioId,MSDK_SENSOR_EXPOSURE_WINDOW_STRUCT *pImageWindow,MSDK_SENSOR_CONFIG_STRUCT *pSensorConfigData);MUINT32 (*SensorClose)(void);MUINT8  arch;void   *psensor_inst; /* IMGSENSOR_SENSOR_INST */
};

　　对应驱动中填充的信息如下：

static struct SENSOR_FUNCTION_STRUCT sensor_func = {open,//打开camera时调用get_info,// 获取sensor的动态信息get_resolution,//获取sensor特定模式下的尺寸feature_control,control,close
};

3、open 函数介绍及其所完成的任务：

　　（1）此函每次打开camera都会调用；

　　（2）读取sensorid，确保I2C通讯正常；

　　（3）调用sensor_init初始化sensor芯片；

　　（4）初始化imgsensor结构体中的变量；

　　（5）读取otp中信息；

static kal_uint32 open(void)
{//获取sensor的ID确认i2c是否正常sensor_id = return_sensor_id();//设置I2C 的速率kdSetI2CSpeed(400);//sensor初始化参数设置sensor_init();//初始化imgsensor结构体imgsensor.autoflicker_en = KAL_FALSE;imgsensor.sensor_mode = IMGSENSOR_MODE_INIT;imgsensor.pclk = imgsensor_info.pre.pclk;imgsensor.frame_length = imgsensor_info.pre.framelength;imgsensor.line_length = imgsensor_info.pre.linelength;imgsensor.min_frame_length = imgsensor_info.pre.framelength;imgsensor.dummy_pixel = 0;imgsensor.dummy_line = 0;imgsensor.ihdr_en = 0;imgsensor.test_pattern = KAL_FALSE;imgsensor.current_fps = imgsensor_info.pre.max_framerate;
}

4、feature_control接口：

（1）获取linelength和pclk：

 case SENSOR_FEATURE_GET_PERIOD:*feature_return_para_16++ = imgsensor.line_length;*feature_return_para_16 = imgsensor.frame_length;*feature_para_len = 4;break;case SENSOR_FEATURE_GET_PIXEL_CLOCK_FREQ:*feature_return_para_32 = imgsensor.pclk;*feature_para_len = 4;break;

获取各个mode的sensor pclk(pixel/s)，PCLK指pixel采样的时钟，

linelength, 结合pclk来计算linetime, 用来换算ae plinetable的exposure time对应的shutter (unit: line,条数)。

（2）set_shutter设置曝光行：

 case SENSOR_FEATURE_SET_ESHUTTER:set_shutter(*feature_data);break;

设置曝光行，曝光行物理上小于frame_length，所以曝光行大于当前frame_length时，frame_length会自动撑长，

帧率降低所以亮度较低时，帧率会下降，因为这时候shutter比较大。每个AE周期会根据AE算法找到的对应pline

table中相应index的exp转换为shutter下给driver。

（3）streaming_control控制sensor输出数据：

 case SENSOR_FEATURE_SET_STREAMING_SUSPEND:pr_info("SENSOR_FEATURE_SET_STREAMING_SUSPEND\n");streaming_control(KAL_FALSE);break;case SENSOR_FEATURE_SET_STREAMING_RESUME:pr_info("SENSOR_FEATURE_SET_STREAMING_RESUME, shutter:%llu\n",*feature_data);if (*feature_data != 0)set_shutter(*feature_data);streaming_control(KAL_TRUE);break;

　　在打开sensor输出数据前，需要先设置shutter。

５、control 模式切换函数：

static kal_uint32 control(enum MSDK_SCENARIO_ID_ENUM scenario_id, MSDK_SENSOR_EXPOSURE_WINDOW_STRUCT *image_window,MSDK_SENSOR_CONFIG_STRUCT *sensor_config_data)
{spin_lock(&imgsensor_drv_lock);imgsensor.current_scenario_id = scenario_id;spin_unlock(&imgsensor_drv_lock);switch (scenario_id) {case MSDK_SCENARIO_ID_CAMERA_PREVIEW:preview(image_window, sensor_config_data);break;case MSDK_SCENARIO_ID_CAMERA_CAPTURE_JPEG:capture(image_window, sensor_config_data);break;case MSDK_SCENARIO_ID_VIDEO_PREVIEW:normal_video(image_window, sensor_config_data);break;case MSDK_SCENARIO_ID_HIGH_SPEED_VIDEO:hs_video(image_window, sensor_config_data);break;case MSDK_SCENARIO_ID_SLIM_VIDEO:slim_video(image_window, sensor_config_data);break;}return ERROR_NONE;
}

以preview为例说明流程：

static kal_uint32 preview(MSDK_SENSOR_EXPOSURE_WINDOW_STRUCT *image_window,MSDK_SENSOR_CONFIG_STRUCT *sensor_config_data)
{
//更新imgsensor结构体信息spin_lock(&imgsensor_drv_lock);imgsensor.sensor_mode = IMGSENSOR_MODE_PREVIEW;imgsensor.pclk = imgsensor_info.pre.pclk;/* imgsensor.video_mode = KAL_FALSE; */imgsensor.line_length = imgsensor_info.pre.linelength;imgsensor.frame_length = imgsensor_info.pre.framelength;imgsensor.min_frame_length = imgsensor_info.pre.framelength;imgsensor.autoflicker_en = KAL_TRUE;spin_unlock(&imgsensor_drv_lock);
//更新寄存器preview_setting();return ERROR_NONE;
}

作者：frank_zyp
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