Problem to setup a serial communication in petalinux

Question

I have to use a rs232 serial communication in a C program with a petalinux OS. And I have problem to read data from my serial. As I am not familiar with linux OS I have searched on internet some example of C program to write and read data on a rs2323.

Here is how I setup my serial

int open_uart() {
    uart1_fd = open("/dev/ttyUL2", O_RDWR | O_NOCTTY | O_NDELAY);
    if (uart1_fd == -1) {
        printf("--- no uart ---\n");
        return 0;
    } else {
        printf("--- open uart ok ---\n");
    }
    struct termios tty;

    tcgetattr(uart1_fd, &tty);

    tty.c_cflag &= ~PARENB;     // Disable parity
    tty.c_cflag &= ~CSTOPB;    // One stop bit
    tty.c_cflag &= ~CSIZE;     // Clear size bits
    tty.c_cflag |= CS8;        // 8 bits per byte
    tty.c_cflag &= ~CRTSCTS;   // No hardware flow control

    tty.c_iflag &= ~(IXON | IXOFF | IXANY); // Disable software flow control
    tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP); // Disable special characters
    tty.c_oflag &= ~OPOST;   // No post-processing
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN); // Disable canonical mode

    tty.c_cc[VTIME] = 10;     // Wait up to 10 deciseconds for data
    tty.c_cc[VMIN] = 0;       // Don't wait for minimum number of characters

    if (cfsetispeed(&tty, B38400) < 0 || cfsetospeed(&tty, B38400) < 0) {
        printf("error\n");
    }
    if (tcsetattr(uart1_fd, TCSANOW, &tty) < 0) {
        printf("error\n");
    }
    return 1;
}

There is no problem to write data but to read if I simply do this

rx_length = read(uart1_fd, (void*) rx_buffer, 32);

rx_length is 0 and nothing is read. To read my data I need to do this

int recvMsg(char* pMsg, int16_t lng) {
    int nb = -1;
    char rx = 0;
    int m = 0;
    memset(pMsg, 0, lng);
    while (rx != 0xfa && m < lng && nb <= 10000) {
        nb++;
        if (read(uart1_fd, &rx, 1) > 0)
            pMsg[m++] = rx;
    }
    printf("Réception de: ");
    for (int i = 0; i < m; i++) {
        printf("%02x ", (uint8_t) pMsg[i]);
    }
    printf("\r\n");
    return m;
}

I suspect my initial configuration is not appropriate. What I expect is that the read function will return only when it has received all the incoming data