Commit 663720b2 authored May 08, 2017 by Jim Kaye

Fix enforcement of sensor's slowest rate

This code calculates a sensor's maximum sample
period in nanoseconds. This is stored as a 64-bit
value, as required for periods greater than ~2.1
seconds.

The calculation was done with 32-bit arithmetic,
sometimes resulting in overflow. This caused the
sensor to run at its maximum rate.

(The requested period is first clipped to the maximum
period. When the maximum period appears negative, it
is always used. The now-negative period is then clipped
to the minimum period, resulting in the sensor's maximum
supported rate.)

Bug: 37465457

Test: Verified correct operation with Goldfish accelerometer,
which has a 60-second maximum period.

Change-Id: Ic75a9dc7c4e7c9ca690eafbfa51ee50540ca5aaf

parent 584bc3ce

services/sensorservice/SensorService.cpp

+1 −2

Original line number	Original line	Diff line number	Diff line
	@@ -1250,7 +1250,7 @@ status_t SensorService::enable(const sp<SensorEventConnection>& connection,
	}		}

	// Check maximum delay for the sensor.		// Check maximum delay for the sensor.
	nsecs_t maxDelayNs = sensor->getSensor().getMaxDelay() * 1000;		nsecs_t maxDelayNs = sensor->getSensor().getMaxDelay() * 1000LL;
	if (maxDelayNs > 0 && (samplingPeriodNs > maxDelayNs)) {		if (maxDelayNs > 0 && (samplingPeriodNs > maxDelayNs)) {
	samplingPeriodNs = maxDelayNs;		samplingPeriodNs = maxDelayNs;
	}		}
	@@ -1511,4 +1511,3 @@ bool SensorService::isOperationRestricted(const String16& opPackageName) {
	}		}

	}; // namespace android		}; // namespace android