Android：光感自动调节亮度

其实其他平台就像MTK，高通也差不多，大同小异，主要搜索关键词：config_autoBrightnessLevels、config_screenBrightnessBacklight，只是文件路径不同。

通过修改sensorhub上报下光感原始数据，或根据实际情况进行调整brightness level根据个人喜好，可以自动调节亮度功能的灵敏度。

展锐的代码路径如下：

device\sprd\roc1\common\overlay\frameworks\base\core\res\res\values\config.xml

    <!-- Array of light sensor LUX values to define our levels for auto backlight brightness support.          The N entries of this array define N  1 zones as follows:           Zone 0:        0 <= LUX < array[0]          Zone 1:        array[0] <= LUX < array[1]          ...          Zone N:        array[N - 1] <= LUX < array[N]          Zone N   1     array[N] <= LUX < infinity           Must be overridden in platform specific overlays -->     <integer-array name="config_autoBrightnessLevels">         <item>16</item>         <item>32</item>         <item>50</item>         <item>100</item>         <item>140</item>         <item>180</item>         <item>240</item>         <item>300</item>         <item>600</item>         <item>800</item>         <item>1000</item>         <item>2000</item>         <item>3000</item>         <item>4000</item>         <item>5000</item>         <item>6000</item>         <item>8000</item>         <item>10000</item>   <item>20000</item>   <item>30000</item>     </integer-array>     <!-- Array of desired screen brightness in nits corresponding to the lux values          in the config_autoBrightnessLevels array. As with config_screenBrightnessMinimumNits and          config_screenBrightnessMaximumNits, the display brightness is defined as the measured          brightness of an all-white image.           If this is defined then:             - config_autoBrightnessLcdBacklightValues should not be defined             - config_screenBrightnessNits must be defined             - config_screenBrightnessBacklight must be defined           This array should have size one greater than the size of the config_autoBrightnessLevels          array. The brightness values must be non-negative and non-decreasing. This must be          overridden in platform specific overlays -->     <array name="config_autoBrightnessDisplayValuesNits">         <item>10.45935</item>   <!-- 0-16 -->         <item>29.25559</item>   <!-- 0-16 -->         <item>29.25559</item>   <!-- 16-32 -->         <item>34.240692</item>  <!-- 32-50 -->         <item>37.514347</item>  <!-- 50-100 -->         <item>40.018696</item>  <!-- 100-140 -->         <item>46.885098</item>  <!-- 140-180 -->         <item>51.626434</item>  <!-- 180-240 -->         <item>58.610405</item>  <!-- 240-300 -->         <item>66.890915</item>  <!-- 300-600 -->         <item>77.61644</item>   <!-- 600-800 -->         <item>90.221886</item>  <!-- 800-1000 -->         <item>105.80314</item>  <!-- 1000-2000 -->         <item>126.073845</item> <!-- 2000-3000 -->         <item>154.16931</item>  <!-- 3000-4000 -->         <item>191.83717</item>  <!-- 4000-5000 -->         <item>240.74442</item>  <!-- 5000-6000 -->         <item>294.84857</item>  <!-- 6000-8000 -->         <item>348.05453</item>  <!-- 8000-10000 -->         <item>394.98703</item>  <!-- 10000-20000 -->   <item>405.2315</item>  <!-- 20000-30000 -->   <item>410.3658</item>  <!-- 30000  -->     </array>      <!-- An array describing the screen's backlight values corresponding to the brightness          values in the config_screenBrightnessNits array.           This array should be equal in size to config_screenBrightnessBacklight. -->     <integer-array name="config_screenBrightnessBacklight">         <item>0</item>         <item>5</item>         <item>10</item>         <item>15</item>         <item>20</item>         <item>25</item>         <item>30</item>         <item>35</item>         <item>40</item>         <item>45</item>         <item>60</item>         <item>75</item>         <item>90</item>         <item>105</item>         <item>120<item>
        <item>135</item>
        <item>150</item>
        <item>165</item>
        <item>180</item>
        <item>195</item>
        <item>210</item>
        <item>225</item>
        <item>240</item>
        <item>255</item>
    </integer-array>

查看光感数据上报原始值节点：

cat /sys/devices/virtual/sprd_sensorhub/sensor_hub/raw_data_als

可以跟一下代码就会发现在kernel下：

kernel4.14\drivers\iio\sprd_hub\shub_core.c

static ssize_t raw_data_als_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct shub_data *sensor = dev_get_drvdata(dev);
	u8 data[2];
	u16 *ptr;
	int err;

	ptr = (u16 *)data;
	if (sensor->mcu_mode <= SHUB_OPDOWNLOAD) {
		dev_err(dev, "mcu_mode == SHUB_BOOT!\n");
		return -EINVAL;
	}

	err = shub_sipc_read(sensor,
			     SHUB_GET_LIGHT_RAWDATA_SUBTYPE, data, sizeof(data));
	if (err < 0) {
		dev_err(dev, "read RegMapR_GetLightRawData failed!\n");
		return err;
	}
	return sprintf(buf, "%d\n", ptr[0]);
}
static DEVICE_ATTR_RO(raw_data_als);