Change SensorEvent data values length in Android Sensor Framework

I am currently developing a driver for an ambient light sensor on a Qualcomm Snapdragon 888 platform.

When I try to interact with the device through the Android Sensor Framework I only get the Lux value (in the onSensorChanged callback the size of the values field in SensorEvent object is 1 whereas multiple data are pushed along with the Lux measure).

When having a look at the proprietary vendor implementation of the HAL I can clearly see that multiple data are being pushed to the HAL event message queue, but only the Lux info is forwarded by the framework.

I guess that somewhere in the AOSP the additional information (raw data in my case) are being discarded / ignored and I can't really find where this operation is done in the codebase.

To summarize, I would like to know which location has to be patched in order to keep these information and be able to use them at application level.

While doing some research I came across this question where users were using some additional info forwarded by the sensor framework for the light sensor: Reading Android RGB light sensor - Galaxy S5

Thank you!

Solution

It took me some time but I managed to get it working applying the following patches:

In frameworks/base/core/java/android/hardware/Sensor.java, update the entry of your sensor in the sSensorReportingModes array with the desired data length:

private static final int[] sSensorReportingModes = {
    ...
    2, // SENSOR_TYPE_LIGHT
    ...
}

In hardware/interfaces/sensors/1.0/default/convert.cpp, update the following methods accordingly:

void convertFromSensorEvent(const sensors_event_t &src, Event *dst) {
    ...
    case SensorType::LIGHT:
        dst->u.data[0] = src.data[0];
        dst->u.data[1] = src.data[1];
        break;
    ...
}

void convertToSensorEvent(const Event &src, sensors_event_t *dst) {        
    ...
    case SensorType::LIGHT:
        dst->data[0] = src.u.data[0];
        dst->data[1] = src.u.data[1];
        break;
    ...
}