串口发送前调用TCIOFLUSH会出现发送数据错乱问题

xielin

背景：贴上部分代码

void* serial_thread() {

    int fd =  open_dev(SERIALPORT_PATH);
    if (fd <=0) {
        printf("open '%s' failed %d!\n", SERIALPORT_PATH, fd);
        close(fd);
        return NULL;
    }
    printf("open %s seccuss\n", SERIALPORT_PATH);
    if (set_speed(fd, SERIALPORT_SPEED) == -1) {
        close_dev(fd);
        return NULL;
    }
    printf("set speed %d seccuss\n", SERIALPORT_SPEED);

    int write_times = 0;
    char write_buf[1024];

    while (test_running && write_times++ < test_times) {
        if (write_flush) {
            tcflush(fd, TCIOFLUSH);
            usleep(flush_time * 1000);
        }
        memset(write_buf, 0, sizeof(write_buf));

        sprintf(write_buf, "%s_%d\n", send_data, write_times);
        int write_len = write(fd, write_buf, strlen(write_buf));
        printf(" write len = %d, str = %s\n", write_len, write_buf);
        usleep(sleep_time * 1000);
    }
    close_dev(fd);
    return NULL;
}



客户反馈使用串口向外部设备发送数据，在每次发送数据前如果使用tcflush(fd, TCIOFLUSH)清空缓存，则会导致发送的数据出现错乱，错乱的图片见附件。
解决办法：关闭对应串口dma传输
        apuart1: serial@11003000 {
                compatible = "mediatek,mt6577-uart";
                reg = <0 0x11003000 0 0x1000>;
                interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_LOW>;
                clocks =  <&clk26m>, <&infracfg_ao CLK_IFR_UART1>;
                clock-names = "baud", "bus";
-                dmas = <&apdma 2
-                                &apdma 3>;
-                dma-names = "tx", "rx";
        };