Merge "USB MIDI: Fix race condition that causes intermittent connections."

        jint card, jint device)

{

    char    path[100];

    int     fd;

    const   int kMaxRetries = 10;

    const   int kSleepMicroseconds = 2000;

    snprintf(path, sizeof(path), "/dev/snd/controlC%d", card);

    int fd = open(path, O_RDWR);

    if (fd < 0) {

        ALOGE("could not open %s", path);

    // This control device may not have been created yet. So we should

    // try to open it several times to prevent intermittent failure

    // from a race condition.

    int retryCounter = 0;

    while ((fd = open(path, O_RDWR)) < 0) {

        if (++retryCounter > kMaxRetries) {

            ALOGE("timed out after %d tries, could not open %s", retryCounter, path);

            return 0;

        } else {

            ALOGW("attempt #%d, could not open %s", retryCounter, path);

            // Increase the sleep interval each time.

            // 10 retries will total 2 * sum(1..10) = 110 milliseconds.

            // Typically the device should be ready in 5-10 milliseconds.

            usleep(kSleepMicroseconds * retryCounter);

        }

    }

    struct snd_rawmidi_info info;