方式一：

adb shell setprop persist.vendor.debug.set.fixedfps xxxx
每次重开camera生效

int32_t QCameraParameters::setPreviewFpsRange(int min_fps,
        int max_fps, int vid_min_fps,int vid_max_fps)
{
    char str[32];
    char value[PROPERTY_VALUE_MAX];
    int fixedFpsValue;
    /*This property get value should be the fps that user needs*/
    property_get("persist.vendor.debug.set.fixedfps", value, "0");
    fixedFpsValue = atoi(value);

    LOGD("E minFps = %d, maxFps = %d , vid minFps = %d, vid maxFps = %d",
                 min_fps, max_fps, vid_min_fps, vid_max_fps);

    if(fixedFpsValue != 0) {
        min_fps = max_fps = fixedFpsValue*1000;
        if (!isHfrMode()) {
             vid_min_fps = vid_max_fps = fixedFpsValue*1000;
        }
    }
    snprintf(str, sizeof(str), "%d,%d", min_fps, max_fps);
    LOGH("Setting preview fps range %s", str);
    updateParamEntry(KEY_PREVIEW_FPS_RANGE, str);
    cam_fps_range_t fps_range;
    memset(&fps_range, 0x00, sizeof(cam_fps_range_t));
    fps_range.min_fps = (float)min_fps / 1000.0f;
    fps_range.max_fps = (float)max_fps / 1000.0f;
    fps_range.video_min_fps = (float)vid_min_fps / 1000.0f;
    fps_range.video_max_fps = (float)vid_max_fps / 1000.0f;

    LOGH("Updated: minFps = %d, maxFps = %d ,"
            " vid minFps = %d, vid maxFps = %d",
             min_fps, max_fps, vid_min_fps, vid_max_fps);

    if ( NULL != m_AdjustFPS ) {
        if (m_ThermalMode == QCAMERA_THERMAL_ADJUST_FPS &&
                !m_bRecordingHint_new) {
            float minVideoFps = min_fps, maxVideoFps = max_fps;
            if (isHfrMode()) {
                minVideoFps = m_hfrFpsRange.video_min_fps;
                maxVideoFps = m_hfrFpsRange.video_max_fps;
            }
            m_AdjustFPS->recalcFPSRange(min_fps, max_fps, minVideoFps,
                                         maxVideoFps, fps_range, m_bRecordingHint_new);
            LOGH("Thermal adjusted Preview fps range %3.2f,%3.2f, %3.2f, %3.2f",
                   fps_range.min_fps, fps_range.max_fps,
                  fps_range.video_min_fps, fps_range.video_max_fps);
        }
    }

    if (ADD_SET_PARAM_ENTRY_TO_BATCH(m_pParamBuf, CAM_INTF_PARM_FPS_RANGE, fps_range)) {
        return BAD_VALUE;
    }

    return NO_ERROR;
}

方式二

固定linecount方式固定帧率 adb shell setprop persist.vendor.camera.sensor.linecount xxx

{
        .x_output = 1296,
        .y_output = 972,
        .line_length_pclk = 750,
        .frame_length_lines = 2000,
        .op_pixel_clk = 180000000,//clk = 450Mhz ,mipi_speed = 900Mbps = 180Mx10bit/2lane
        .binning_factor = 2,
        .min_fps = 10.00,
        .max_fps = 30.00,
        .mode = SENSOR_DEFAULT_MODE,
        .offset_x = 0,
        .offset_y = 0,
        .scale_factor = 0,
        .data_rate =900000000ULL * 2,
      },

fixed_fps = line_length_pclk * frame_length_lines * max_fps / line_length_pclk / cur_line_count.
注意要开启相应的宏ENABLE_MANUAL_EXPOSURE_UPDATE

#ifdef ENABLE_MANUAL_EXPOSURE_UPDATE
  if(updateExtGain(&ext_real_gain) == SENSOR_SUCCESS)
    real_gain = ext_real_gain;

  if(updateExtLinecount(&ext_linecount) == SENSOR_SUCCESS)
    linecount = ext_linecount;
#endif

==>
static int32_t updateExtLinecount(uint32_t *linecount)
{
  char ext_linecount[PROPERTY_VALUE_MAX];

  RETURN_ERROR_ON_NULL(linecount);

  property_get("persist.vendor.camera.sensor.linecount", ext_linecount, "0");
  *linecount = atoi(ext_linecount);
  if (*linecount > 0) {
    SHIGH("Updated linecount: %d", *linecount);
    return SENSOR_SUCCESS;
  }

    return SENSOR_FAILURE;
}