AM62P: UART with DMA mode: cannot receive data when communicating with GMSL

Part Number: AM62P
Other Parts Discussed in Thread: SYSCONFIG

Hi,

I try to establish a communication between AM62P and a GMSL chip on cusomized board and the MCU+SDK version I am using is 11.01.01.08. 

The current situation is that I could implement uart_echo example successfully. In this project, I used self-encapsulated API for uart transmission. The snipped code is attached below.  

 status = SemaphoreP_constructBinary(&gUartWriteDoneSem_gmsl1, 0);
  status = SemaphoreP_constructBinary(&gUartReadDoneSem_gmsl1, 0);

uint8_t gUartTxBuffer[200] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));
    uint8_t gUartRxBuffer[8] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)));
    strncpy(&gUartTxBuffer[0],"[MCU] uart DMA test. Please enter\r\n", 200);
    length = strlen(&gUartTxBuffer[0]);
    status = uart_txEncap(0, gUartTxBuffer, length);

    status = uart_rxEncap(0, gUartRxBuffer, 8);

    status = uart_txEncap(0, gUartRxBuffer, 8);
    
    strncpy(&gUartTxBuffer[0],"\r\n[MCU] At the end of test... \r\n", 200);
    length = strlen(&gUartTxBuffer[0]);
    status = uart_txEncap(0, gUartTxBuffer, length);

The snipped code for self-encapsulated API is shown below.

int32_t uart_txEncap(uint8_t u8_core_sel, uint8_t *tx_AppBuffer, uint32_t tx_bufSize)
{
    int32_t status;
    UART_Transaction uartTrans;

    /* Cache write-back before DMA - ensures DMA reads updated data from memory */
    CacheP_wb((void *)&tx_AppBuffer[0], tx_bufSize, CacheP_TYPE_ALL);

    UART_Transaction_init(&uartTrans);
    uartTrans.count = tx_bufSize;
    uartTrans.buf = &tx_AppBuffer[0U];


    status = UART_write(gUartHandle[u8_core_sel], &uartTrans);
    UART_flushTxFifo(gUartHandle[u8_core_sel]);

    if (u8_core_sel == 0) 
    {
        SemaphoreP_pend(&gUartWriteDoneSem_gmsl1, SystemP_WAIT_FOREVER);
    }
    else if (u8_core_sel == 1)
    {
        SemaphoreP_pend(&gUartWriteDoneSem_gmsl2, SystemP_WAIT_FOREVER);
    } 

    if (SystemP_SUCCESS != (status))
    {
        return status;
    }
    else
    {
        return SystemP_SUCCESS;
    }
}

int32_t uart_rxEncap(uint8_t u8_core_sel, uint8_t *rx_AppBuffer, uint32_t rx_bufSize, uint32_t semaPend_us)
{
    int32_t status;
    UART_Transaction uartTrans;
    uint32_t lineStatus, atLeastCharInFifo = 0;

    /* Cache write-back before DMA - ensures DMA reads updated data from memory */
    CacheP_wbInv((void *)&rx_AppBuffer[0], rx_bufSize, CacheP_TYPE_ALL);

    UART_Transaction_init(&uartTrans);
    uartTrans.count = rx_bufSize;
    uartTrans.buf = &rx_AppBuffer[0U];

    status = UART_read(gUartHandle[u8_core_sel], &uartTrans);

    if (u8_core_sel == 0) 
    {
        SemaphoreP_pend(&gUartReadDoneSem_gmsl1, SystemP_WAIT_FOREVER);
    }
    else if (u8_core_sel == 1)
    {
        SemaphoreP_pend(&gUartReadDoneSem_gmsl2, SystemP_WAIT_FOREVER);
    } 

    if (SystemP_SUCCESS != (status))
    {
        return status;
    }
    else
    {
        return SystemP_SUCCESS;
    }
}

The test results is attahced below and I think everything work good. For sysconfig configuration, the baud rate is 115200, the uart is configured as DMA+callback mode, the peripheral hardware I used is USART3. 


Until now, everything works fine and I try to use those encapsulated API to communicate with GMSL. The sysconfig does not need any change except its baud rate is 1M Hz. But I found I cannot receive the response from GMSL. When I debugging, I found status of uart_tx is success and the program is blocking in uart_rxEncap, which implies soc does not receive the response of GMSL. However, I could measure the correct signal on UART_RX line as below. I wonder why this happens?

uint8_t tx_buf1[4] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)))= {0x79, 0xC5, 0x08, 0x01};
    uint8_t rx_buf1[2] __attribute__((aligned(CacheP_CACHELINE_ALIGNMENT)))= { 0 };
    status = uart_txEncap(0, tx_buf1, 4);
    status = uart_rxEncap(0, rx_buf1, 2);

Regards,

Bomiao