QSerialPort::write() issue with Linux

Hello,

I'm working on embedded system using an STM32 microcontroller. The micro has USB interface configured as CDC ACM Virtual COM.
After /dev/ttyACM0 is opened by QSerialPort::open(), I sent a simple string to micro with QSerialPort::write():

serial->write("who");

This Function is called by microcontroller firmware when data are present in receive buffer:

void USBD_CDC0_ACM_DataReceived(uint32_t len)
{
   int32_t cnt;
   (void)(len);
    cnt = USBD_CDC_ACM_ReadData(0U, uart_rx_buf, 64);
    if (cnt > 0) {
                    osSignalSet(T_LED_Thread, 0x01);
    }
{color:#205081}}

With QT in Windows it works well: the function is called and in the uart_rx_buff variable the string "who" is present. cnt variable is 3.
With QT in Linux it works diffent: the function is called for 3 times. uart_rx_buf contans one char sequentially "w" "h" "o" and cnt is always 1.

I've done a simple mod in qserialport_unix.cpp:

 

static inline void qt_set_common_props(termios *tio, QIODevice::OpenMode m)
{
#ifdef Q_OS_SOLARIS
     tio->c_iflag &= ~(IMAXBEL|IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IXON);
     tio->c_oflag &= ~OPOST;
     tio->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
     tio->c_cflag &= ~(CSIZE|PARENB);
     tio->c_cflag |= CS8;
#else
    ::cfmakeraw(tio);
    //-------------------------------------------------------------------------------------
    // LINUX write raw resolved
    //-------------------------------------------------------------------------------------
    tio.c_cflag |= CREAD;
    tio.c_lflag &= (~(ICANON|ECHO|ECHOE|ECHOK|ECHONL|ISIG));
    tio.c_iflag &= (~(INPCK|IGNPAR|PARMRK|ISTRIP|ICRNL|IXANY));
    tio.c_oflag &= (~OPOST);
    //-------------------------------------------------------------------------------------

#endif

    tio->c_cflag |= CLOCAL;
    tio->c_cc[VTIME] = 0;
    tio->c_cc[VMIN] = 0;

    if (m & QIODevice::ReadOnly)
         tio->c_cflag |= CREAD;

{color:#205081}}

I took this settings from this old project : https://github.com/qextserialport/qextserialport/blob/master/src/qextserialport_unix.cpp

With this setting it works well with microcontroller.
I'm not an expert programmer, only an hobbyist, I don't now if is a right solution and how to reproduce bug without interfacing to the microcontroller but QSerialPort::write() works now.

Thanks and sorry for my poor english.
Regards, Massimo.