[Sense HAT driver] Unable to read to I2C device

• Component affected:

  • Distribution
    • Installer name: kura_3.2.0_raspberry-pi-2-3-nn_installer.deb
    • Platform: Raspberry Pi 3
    • Kura version affected: 3.2.0
    • Java version: openjdk version "1.8.0_171" OpenJDK Runtime Environment (build 1.8.0_171-8u171-b11-1~deb9u1-b11) OpenJDK Client VM (build 25.171-b11, mixed mode)
    • Host OS: Raspbian Stretch Lite
  • Add-ons
    • Name: org.eclipse.kura.example.driver.sensehat
    • Version: 1.0.0
    • URL: https://marketplace.eclipse.org/content/sensehat-example-driver-eclipse-kura

• Textual description of the issue:

I am trying to use the Sense HAT driver to read data from the environmental sensors and send it to a Kapua instance. I installed the driver mentioned in the form but when I try to add a new driver I get some errors (see kura.log) saying that it is not possible to read or write to the I2C device. I have already enabled the I2C kernel module using the raspi-config tool and I confirm that the Sense HAT works because I am able to measure using the python library.

[nicolatimeus]

Replicated by installing the openjdk-8-jre-headless package which provides the JVM version you reported. In my setup the driver works if the oracle-java8-jdk package is installed, which provides the following java version:

java version "1.8.0_65"
Java(TM) SE Runtime Environment (build 1.8.0_65-b17)
Java HotSpot(TM) Client VM (build 25.65-b01, mixed mode)

There might some issue regarding using the jdk.dio library either with openjdk itself or with some JVM version more recent than 1.8.0_65.

Moreover, I’ve found this by digging into the jdk.dio source in Kura repo:

The com.oracle.dio.impl.Handle.tryLock(int) method, which is called in the code path that leads to the reported exception has the following signature [1]:

public native boolean tryLock(int timeout);

And this is its native implementation [2]:

/*
 * Tries locking the device.
 * Class:     com_oracle_dio_impl_Handle
 * Method:    tryLock
 */
JNIEXPORT void JNICALL Java_com_oracle_dio_impl_Handle_tryLock
  (JNIEnv* env, jobject obj, jint timeout) {
    device_reference device = getDeviceReferenceFromHandleObject(env, obj);
    if (device != INVALID_DEVICE_REFERENCE) {
        //  add an implementation
    }
}

The native function returns void instead of a jboolean, and its implementation looks incomplete. This is quite suspicious.

[1] https://github.com/eclipse/kura/blob/develop/target-platform/jdk.dio-parent/src/dev/src/se/classes/com/oracle/dio/impl/Handle.java#L41 [2] https://github.com/eclipse/kura/blob/develop/target-platform/jdk.dio-parent/src/dev/src/se/native/com/oracle/dio/dio_common.cpp#L458

[cdealti]

Add the necessary documentation