Only requantize sensor max range if significant
The previous computation that decided whether to adjust the sensor's
reported maximum range if not a multiple of the resolution was
susceptible to floating point error (e.g. considering 5.0 as not a
multiple of 0.1), so rework this to only update the maximum range and
print a warning log if the maximum range would be changed significantly
after requantization. We define significant here as resolution/8 (i.e.
the target quantization level).
Also, make the reported power clamping log more helpful.
Fixes: 182828004
Test: compare SensorService startup logs before & after change
Change-Id: I44e399a7aca6fe8ff02bd2840525c95798cda1f4
diff --git a/services/sensorservice/SensorDevice.cpp b/services/sensorservice/SensorDevice.cpp
index d8e8b52..5d6f8c7 100644
--- a/services/sensorservice/SensorDevice.cpp
+++ b/services/sensorservice/SensorDevice.cpp
@@ -132,8 +132,6 @@
}
void SensorDevice::initializeSensorList() {
- float minPowerMa = 0.001; // 1 microAmp
-
checkReturn(mSensors->getSensorsList(
[&](const auto &list) {
const size_t count = list.size();
@@ -151,13 +149,18 @@
// Don't crash in this case since CTS will verify that devices don't go to
// production with a resolution of 0.
if (sensor.resolution != 0) {
- double promotedResolution = sensor.resolution;
- double promotedMaxRange = sensor.maxRange;
- if (fmod(promotedMaxRange, promotedResolution) != 0) {
- ALOGW("%s's max range %f is not a multiple of the resolution %f",
- sensor.name, sensor.maxRange, sensor.resolution);
- SensorDeviceUtils::quantizeValue(
- &sensor.maxRange, promotedResolution);
+ float quantizedRange = sensor.maxRange;
+ SensorDeviceUtils::quantizeValue(
+ &quantizedRange, sensor.resolution, /*factor=*/ 1);
+ // Only rewrite maxRange if the requantization produced a "significant"
+ // change, which is fairly arbitrarily defined as resolution / 8.
+ // Smaller deltas are permitted, as they may simply be due to floating
+ // point representation error, etc.
+ if (fabsf(sensor.maxRange - quantizedRange) > sensor.resolution / 8) {
+ ALOGW("%s's max range %.12f is not a multiple of the resolution "
+ "%.12f - updated to %.12f", sensor.name, sensor.maxRange,
+ sensor.resolution, quantizedRange);
+ sensor.maxRange = quantizedRange;
}
} else {
// Don't crash here or the device will go into a crashloop.
@@ -166,10 +169,11 @@
}
// Sanity check and clamp power if it is 0 (or close)
- if (sensor.power < minPowerMa) {
- ALOGI("Reported power %f not deemed sane, clamping to %f",
- sensor.power, minPowerMa);
- sensor.power = minPowerMa;
+ constexpr float MIN_POWER_MA = 0.001; // 1 microAmp
+ if (sensor.power < MIN_POWER_MA) {
+ ALOGI("%s's reported power %f invalid, clamped to %f",
+ sensor.name, sensor.power, MIN_POWER_MA);
+ sensor.power = MIN_POWER_MA;
}
mSensorList.push_back(sensor);
diff --git a/services/sensorservice/SensorDeviceUtils.h b/services/sensorservice/SensorDeviceUtils.h
index 1309971..255f7e1 100644
--- a/services/sensorservice/SensorDeviceUtils.h
+++ b/services/sensorservice/SensorDeviceUtils.h
@@ -32,16 +32,15 @@
namespace android {
namespace SensorDeviceUtils {
-// Quantizes a single value using a sensor's resolution.
-inline void quantizeValue(float *value, double resolution) {
+// Quantizes a single value to (a fractional factor of) a sensor's resolution. Typically we
+// increase the value of the sensor's nominal resolution to ensure that sensor accuracy
+// improvements, like runtime calibration, are not masked during requantization.
+inline void quantizeValue(float *value, double resolution, double factor = 0.125) {
if (resolution == 0) {
return;
}
- // Increase the value of the sensor's nominal resolution to ensure that
- // sensor accuracy improvements, like runtime calibration, are not masked
- // during requantization.
- double incRes = 0.125 * resolution;
+ double incRes = factor * resolution;
*value = round(static_cast<double>(*value) / incRes) * incRes;
}