Accessing kernel device from Qt application for Android

[Munkhtamir Oyumaa]

Hello Guys,

I have question about how did you access to kernel device using ioctl when you use Qt Android.

The application can just open device but couldn't set configuration using "ioctl" when I run my code.

I have attached my code below.

int FMObject::openDevice(const char *devName)

{

    struct stat st;

    if(FM_FAILED == stat(devName, &st))

    {

        qDebug() << QString("Cannot identify %1: %2, %3")

                    .arg(devName)

                    .arg(errno)

                    .arg(strerror(errno));

        return FM_FAILED;

    }

    if(!S_ISCHR(st.st_mode)) {

        qDebug() << QString("%s is not a valid device").arg(devName);

        return FM_FAILED;

    }

    fd = open(devName, O_RDONLY | O_NONBLOCK);

    if(FM_FAILED == fd)

    {

        qDebug() << QString("Cannot open %1: %2, %3")

                    .arg(devName)

                    .arg(errno)

                    .arg(strerror(errno));

        if(EACCES == errno)

        {

            qDebug() << QString("Insufficient permissions on %1: %2, %3")

                        .arg(devName)

                        .arg(errno)

                        .arg(strerror(errno));

        }

        return FM_FAILED;

    }

    qDebug() << "FD number: " << fd;

    return FM_SUCCESS;

}

int FMObject::setFrequency(float frequency)

{

    qDebug() << "Passed frequency from QML: " << frequency;

    /* convert MHz to Hz*/

    int n_freq = (frequency * 1000000) / 62.5;

    freq.tuner = 0;

    freq.frequency = n_freq;

    freq.type = V4L2_TUNER_RADIO;

    if (ioctl(fd, VIDIOC_S_FREQUENCY, &freq) < 0)

    {

        qDebug() << "ioctl: set frequency";

        qDebug() << "We can't continue without a frequency. Aborting.\n";

        exit(1);

    }

    return FM_SUCCESS;

}

int FMObject::setStart()

{

    system("tinymix 38 0");

    system("tinymix 41 0");

    system("tinymix 48 0");

    system("tinymix 51 0");

    system("tinymix 39 1");

    seek.tuner = 0;

    seek.type = V4L2_TUNER_RADIO;

    seek.wrap_around = 1;

    control.id = V4L2_CID_AUDIO_MUTE;

    control.value = 0;

    if (ioctl(fd, VIDIOC_S_CTRL, &control) < 0) {

        qDebug() << "ioctl: set: mute off";

        qDebug() << "We can't continue without turns mute to off. Aborting";

//        exit(1);

    }

    if (ioctl(fd, VIDIOC_G_TUNER, &tuner) < 0) {

        qDebug() << "ioctl: set: get tuner";

        qDebug() << "We can't continue without a tuner. Aborting";

        exit(1);

    }

    control.id = V4L2_CID_AUDIO_VOLUME;

    control.value = 15;

    if (ioctl(fd, VIDIOC_S_CTRL, &control) < 0) {

        qDebug() << "ioctl: set: set volume";

        qDebug() << "Using the default volume level. Aborting";

        return FM_FAILED;

    }

    return FM_SUCCESS;

}

int FMObject::setDown()

{

    control.id = V4L2_CID_AUDIO_MUTE;

    control.value = 1;

    if (ioctl(fd, VIDIOC_S_CTRL, &control) < 0)

    {

        qDebug() << "radio disable";

        qDebug() << "Failed to disable the radio";

    }

    qDebug() << "Exiting..bye!\n";

    return FM_SUCCESS;

}