ov5640_read_reg16
ret = ov5640_read_reg16(sensor, OV5640_REG_AEC_PK_REAL_GAIN, &gain);
ret = ov5640_read_reg16(sensor, OV5640_REG_TIMING_HTS, &hts);
ret = ov5640_read_reg16(sensor, OV5640_REG_TIMING_VTS, &vts);
ret = ov5640_read_reg16(sensor, OV5640_REG_AEC_PK_VTS,
ret = ov5640_read_reg16(sensor, OV5640_REG_CHIP_ID, &chip_id);