The purpose of the 'if ((hspi->hdmatx->Mode & DMA_LINKEDLIST) == DMA_LINKEDLIST)' in STM32U5 SPI transfer with DMA APIs

[diverger]

Hi,

I'm trying to combine the SPI and GPDMA on STM32U5. In the various SPI transfer APIs with suffix '_DMA', I can see the code below:

  /* Enable the Tx DMA Stream/Channel */
  if ((hspi->hdmatx->Mode & DMA_LINKEDLIST) == DMA_LINKEDLIST)
  {
    if (hspi->hdmatx->LinkedListQueue != NULL)
    {
      /* Set DMA data size */
      hspi->hdmatx->LinkedListQueue->Head->LinkRegisters[NODE_CBR1_DEFAULT_OFFSET] = hspi->TxXferCount;

      /* Set DMA source address */
      hspi->hdmatx->LinkedListQueue->Head->LinkRegisters[NODE_CSAR_DEFAULT_OFFSET] = (uint32_t)hspi->pTxBuffPtr;

      /* Set DMA destination address */
      hspi->hdmatx->LinkedListQueue->Head->LinkRegisters[NODE_CDAR_DEFAULT_OFFSET] = (uint32_t)&hspi->Instance->TXDR;

      status = HAL_DMAEx_List_Start_IT(hspi->hdmatx);
    }
    else
    {
      status = HAL_ERROR;
    }
  }
  else
  {
    status = HAL_DMA_Start_IT(hspi->hdmatx, (uint32_t)hspi->pTxBuffPtr, (uint32_t)&hspi->Instance->TXDR,
                              hspi->TxXferCount);
  }

It seems the code try to support the 'DMA_LINKEDLIST' mode. But can't find a way to set it to 'DMA_LINKEDLIST' in the .ioc file. So, how ST expect us to use this mode?

Thanks.

[Imen.D · Accepted solution]

Hello @diverger ,

You can specify the DMA_LINKEDLIST mode through GPDMA1 Mode and configuration on STM32CubeMX (please see attachment files).
The Execution Mode can be: Circular or Linear (By Default) 

• Circular Mode :

handle_GPDMA1_Channel15.InitLinkedList.LinkedListMode = DMA_LINKEDLIST_CIRCULAR;
#define DMA_LINKEDLIST_CIRCULAR (DMA_LINKEDLIST | (0x01U)​

• Linear Mode :

handle_GPDMA1_Channel15.InitLinkedList.LinkedListMode = DMA_LINKEDLIST_NORMAL;
#define DMA_LINKEDLIST_NORMAL DMA_LINKEDLIST​

[Imen.D]

Hi @diverger ,

Did the solution shared solve your problem?

I'll be waiting for your feedback 🙂