stm32H7 HAL库中存在的bug

stm32H7 hal 库里面的以太网代码，坑了鱼鹰很多次（不知道最新版是否已经修复了这些bug），这里分享一篇网上的文章，因为鱼鹰也遇到过，靠它解决了其中一个编译优化问题，在此感谢作者。不过hal库里面远不止这些bug（主要是项目环境太复杂了，一般情况很难触发），还有更多bug没在此文章描述，而鱼鹰碰到了......

问题

最近在调试STM32H750+LAN8720，搞了大半天终于移植好LwIP了，ping也能ping通，TCP测试也成功。本来以为ST的HAL库终于省心了，结果我将编译优化开到最大…

…直接ping都ping不通了。后来发现HAL库有很大问题。(果然HAL库还是不省心，生成的代码只有初始化能用)

后面发现，HAL库有两个隐患:

1、对描述符的处理有问题

2、因为单片机是Cortex-M7，有Cache和单片机会乱序执行和乱序访问内存，乱序访问对发送/接收描述符 操作有很大的隐患

后面对这些问题详细描述

原因

问题1 HAL库的隐患1 处理方式

我感觉HAL库处理数据描述符的方式似乎很有问题，例如

SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_OWN);//居然在这里将描述符权限给了ETH


if(dmarxdesclist->ItMode != 0U)
{
  SET_BIT(dmarxdesc->DESC3,ETH_DMARXNDESCRF_IOC);//描述符都给了ETH居然还要修改
}

这是stm32h7xx_hal_eth.c中

HAL_StatusTypeDef HAL_ETH_BuildRxDescriptors(ETH_HandleTypeDef *heth)

的一段代码，描述符的OWN在我看来应该是最后才设置的，因为它是标记描述符当前是ETH所有还是用户(CPU等其他玩意)所有，但从这段代码看来，它把描述符归还ETH后居然还对这个描述符进行修改，这是要趁ETH不注意吗，如果真是这样，ETH还真的能正常运行！但是这无疑是一个安全隐患。一个直接体现就是我把编译优化打开(-O3)以太网通信就出问题了。

并且这种操作在HAL库里随处可见，简直恐怖如斯

估摸着ST的人以为写入ETH->DMACRDTPR或者ETH->DMACTDTPR(用于告诉ETH描述符有更新)描述符才会生效，但我看了文档的描述，如果应用程序能一直更新描述符，即使不写入这个寄存器，ETH还是会接着发送，即描述符的OWN位的设置为1代表着描述符归ETH所有，送出去的描述符泼出去的水，用户不应该再进行修改，直到OWN被ETH清零。那ETH->DMACRDTPR或者ETH->DMACTDTPR的用处是什么呢？为了减少ETH对总线的占用，如果ETH检测不到有效的描述符(OWN都为0)，ETH将不再访问内存，所以需要一个机制来告诉ETH描述符有更新，该干活了。

而这个机制就是写入ETH->DMACRDTPR(接收描述符)或者ETH->DMACTDTPR(发送描述符)，这两个寄存器除了标记最后一个描述符的地址，还用于告诉ETH描述符有更新。

问题2 HAL库的隐患2 没有处理Cortex-M7的乱序访问和Cache的问题

正常来说，CPU的乱序执行是不会影响外设操作的。因为外设寄存器的内存类型默认为Device(还要一个类似的属性为Strongly-ordered)，这意味着乱序执行无论在怎么乱，它都会保证对这些内存正确的顺序(在代码中的执行顺序)访问。

但巧了，描述符的存放位置不在这些内存区域，它只能放在D2域的SRAM中(ETH的手只能够着这些地方)，而且这些SRAM的内存类型默认为Normal，而为了效率，CPU会对这些区域的内存乱序访问(这样关键的OWN位可能提前也可能延后被写入)，这肯定不是我们希望的。

对于开启了Cache的情况，这将变得更加复杂，可能写入的数据都没有实实在在的写入内存中。

解决方法

对于问题1，对描述符操作的代码没多少，我就自己手动修改了stm32h7xx_hal_eth.c中的相关代码(修改过的部分在后面放出)，保证代码的顺序是没问题的。主要修改OWN相关的和ETH->DMACRDTPR和ETH->DMACTDTPR相关的。

对于问题2，我是这么处理的：

配置MPU，将描述符，数据缓存所在的内存区域配置为不缓冲(Buffer)，不缓存(Cache)，TEX配置为LEVEL1(0x01)，这样这些内存就配置为了Normal，但不再受Cache的影响(这保证了一个性能的平衡，因为对于CortexM7,CleanCache操作步骤太多，虽然就调用了一个内联的函数，但其中是写一次寄存器Clean一个Cache行，整个Cache需要512次写操作还有其他相关的计算，还不如不Cache这些地方的内存，而使用Normal属性能加快内存访问速度（它似乎能把多个连续单字节的访问打包成32Bit的访问，应该是乱序访问的功劳，这个特性是我调试SDRAM测试它的速度时发现的，即使没有使能Cache，配置成Normal的访问速度比Device要快）)

在设置/清零OWN操作的前后加入__DMB()内存隔离指令(要大写的，自带编译隔离，防止这个指令被编译器重排，没想到吧，编译器也会把你的指令打乱)

LwIP的版本为2.1.0

修改完之后，单片机端使用socket API创建的tcp服务器，单向传输10MB/s，相当于80Mbps带宽，离物理能达到的100Mbps还差一点，但CPU占用率已经达到了80，90多(TCP应该比较消耗性能吧)，估计协议和性能的损耗比较大。

修改的代码

只需要修改stm32h7xx_hal_eth.c的代码

发送的修改

发送相关的有三个函数被修改

static uint32_t ETH_Prepare_Tx_Descriptors(ETH_HandleTypeDef *heth, ETH_TxPacketConfig *pTxConfig, uint32_t ItMode)
{
  ETH_TxDescListTypeDef *dmatxdesclist = &heth->TxDescList;
  uint32_t descidx = dmatxdesclist->CurTxDesc;
  uint32_t firstdescidx = dmatxdesclist->CurTxDesc;
  uint32_t descnbr = 0, idx;
  ETH_DMADescTypeDef *dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[descidx];


  ETH_BufferTypeDef  *txbuffer = pTxConfig->TxBuffer;
  uint32_t           bd_count = 0;


  /* Current Tx Descriptor Owned by DMA: cannot be used by the application  */
  if((READ_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCWBF_OWN) == ETH_DMATXNDESCWBF_OWN) || (dmatxdesclist->PacketAddress[descidx] != NULL))
  {
    return HAL_ETH_ERROR_BUSY;
  }


  /***************************************************************************/
  /*****************    Context descriptor configuration (Optional) **********/
  /***************************************************************************/
  /* If VLAN tag is enabled for this packet */
  if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_VLANTAG) != 0U)
  {
    /* Set vlan tag value */
    MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXCDESC_VT, pTxConfig->VlanTag);
    /* Set vlan tag valid bit */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_VLTV);
    /* Set the descriptor as the vlan input source */
    SET_BIT(heth->Instance->MACVIR, ETH_MACVIR_VLTI);


    /* if inner VLAN is enabled */
    if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_INNERVLANTAG) != 0U)
    {
      /* Set inner vlan tag value */
      MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXCDESC_IVT, (pTxConfig->InnerVlanTag << 16));
      /* Set inner vlan tag valid bit */
      SET_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_IVLTV);


      /* Set Vlan Tag control */
      MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXCDESC_IVTIR, pTxConfig->InnerVlanCtrl);


      /* Set the descriptor as the inner vlan input source */
      SET_BIT(heth->Instance->MACIVIR, ETH_MACIVIR_VLTI);
      /* Enable double VLAN processing */
      SET_BIT(heth->Instance->MACVTR, ETH_MACVTR_EDVLP);
    }
  }


  /* if tcp segmentation is enabled for this packet */
  if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_TSO) != 0U)
  {
    /* Set MSS value */
    MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXCDESC_MSS, pTxConfig->MaxSegmentSize);
    /* Set MSS valid bit */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_TCMSSV);
  }


  if((READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_VLANTAG) != 0U)|| (READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_TSO) != 0U))
  {
    /* Set as context descriptor */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_CTXT);
    /* Set own bit */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_OWN);
    /* Increment current tx descriptor index */
    INCR_TX_DESC_INDEX(descidx, 1U);
    /* Get current descriptor address */
    dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[descidx];


    descnbr += 1U;


    /* Current Tx Descriptor Owned by DMA: cannot be used by the application  */
    if(READ_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCWBF_OWN) == ETH_DMATXNDESCWBF_OWN)
    {
      dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[firstdescidx];
      /* Clear own bit */
      CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXCDESC_OWN);


      return HAL_ETH_ERROR_BUSY;
    }
  }


  /***************************************************************************/
  /*****************    Normal descriptors configuration     *****************/
  /***************************************************************************/


  descnbr += 1U;


  /* Set header or buffer 1 address */
  WRITE_REG(dmatxdesc->DESC0, (uint32_t)txbuffer->buffer);
  /* Set header or buffer 1 Length */
  MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B1L, txbuffer->len);


  if(txbuffer->next != NULL)
  {
    txbuffer = txbuffer->next;
    /* Set buffer 2 address */
    WRITE_REG(dmatxdesc->DESC1, (uint32_t)txbuffer->buffer);
    /* Set buffer 2 Length */
    MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B2L, (txbuffer->len << 16));
  }
  else
  {
    WRITE_REG(dmatxdesc->DESC1, 0x0);
    /* Set buffer 2 Length */
    MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B2L, 0x0U);
  }


  if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_TSO) != 0U)
  {
    /* Set TCP Header length */
    MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_THL, (pTxConfig->TCPHeaderLen << 19));
    /* Set TCP payload length */
    MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_TPL, pTxConfig->PayloadLen);
    /* Set TCP Segmentation Enabled bit */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_TSE);
  }
  else
  {
    MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_FL, pTxConfig->Length);


    if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_CSUM) != 0U)
    {
      MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_CIC, pTxConfig->ChecksumCtrl);
    }


    if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_CRCPAD) != 0U)
    {
      MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_CPC, pTxConfig->CRCPadCtrl);
    }
  }


  if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_VLANTAG) != 0U)
  {
    /* Set Vlan Tag control */
    MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_VTIR, pTxConfig->VlanCtrl);
  }


  /* Mark it as First Descriptor */
  SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_FD);
  /* Mark it as NORMAL descriptor */
  CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_CTXT);


  /* If source address insertion/replacement is enabled for this packet */
  if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_SAIC) != 0U)
  {
    MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_SAIC, pTxConfig->SrcAddrCtrl);
  }


  /* only if the packet is split into more than one descriptors > 1 */
  while (txbuffer->next != NULL)
  {
    /* Clear the LD bit of previous descriptor */
    CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_LD);
    __DMB();//修改!!
    /* set OWN bit of Last descriptor */
    SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_OWN);
    __DMB();//修改!!


    /* Increment current tx descriptor index */
    INCR_TX_DESC_INDEX(descidx, 1U);
    /* Get current descriptor address */
    dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[descidx];


    /* Clear the FD bit of new Descriptor */
    CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_FD);


    /* Current Tx Descriptor Owned by DMA: cannot be used by the application  */
    if((READ_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_OWN) == ETH_DMATXNDESCRF_OWN) || (dmatxdesclist->PacketAddress[descidx] != NULL))
    {
      descidx = firstdescidx;
      dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[descidx];


      /* clear previous desc own bit */
      for(idx = 0; idx < descnbr; idx ++)
      {
        __DMB();//修改!!
        CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_OWN);
        __DMB();//修改!!


        /* Increment current tx descriptor index */
        INCR_TX_DESC_INDEX(descidx, 1U);
        /* Get current descriptor address */
        dmatxdesc = (ETH_DMADescTypeDef *)dmatxdesclist->TxDesc[descidx];
      }


      return HAL_ETH_ERROR_BUSY;
    }


    descnbr += 1U;


    /* Get the next Tx buffer in the list */
    txbuffer = txbuffer->next;


    /* Set header or buffer 1 address */
    WRITE_REG(dmatxdesc->DESC0, (uint32_t)txbuffer->buffer);
    /* Set header or buffer 1 Length */
    MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B1L, txbuffer->len);


    if (txbuffer->next != NULL)
    {
      /* Get the next Tx buffer in the list */
      txbuffer = txbuffer->next;
      /* Set buffer 2 address */
      WRITE_REG(dmatxdesc->DESC1, (uint32_t)txbuffer->buffer);
      /* Set buffer 2 Length */
      MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B2L, (txbuffer->len << 16));
    }
    else
    {
      WRITE_REG(dmatxdesc->DESC1, 0x0);
      /* Set buffer 2 Length */
      MODIFY_REG(dmatxdesc->DESC2, ETH_DMATXNDESCRF_B2L, 0x0U);
    }


    if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_TSO) != 0U)
    {
      /* Set TCP payload length */
      MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_TPL, pTxConfig->PayloadLen);
      /* Set TCP Segmentation Enabled bit */
      SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_TSE);
    }
    else
    {
      /* Set the packet length */
      MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_FL, pTxConfig->Length);


      if(READ_BIT(pTxConfig->Attributes, ETH_TX_PACKETS_FEATURES_CSUM) != 0U)
      {
        /* Checksum Insertion Control */
        MODIFY_REG(dmatxdesc->DESC3, ETH_DMATXNDESCRF_CIC, pTxConfig->ChecksumCtrl);
      }
    }


    bd_count += 1U;


    /* Mark it as NORMAL descriptor */
    CLEAR_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_CTXT);
    
  }


  if(ItMode != ((uint32_t)RESET))
  {
    /* Set Interrupt on completion bit */
    SET_BIT(dmatxdesc->DESC2, ETH_DMATXNDESCRF_IOC);
  }
  else
  {
    /* Clear Interrupt on completion bit */
    CLEAR_BIT(dmatxdesc->DESC2, ETH_DMATXNDESCRF_IOC);
  }


  /* Mark it as LAST descriptor */
  SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_LD);


  __DMB();//修改!!


  /* Set Own bit For End Desc */
  SET_BIT(dmatxdesc->DESC3, ETH_DMATXNDESCRF_OWN);
  
  /* Save the current packet address to expose it to the application */
  dmatxdesclist->PacketAddress[descidx] = dmatxdesclist->CurrentPacketAddress;


  dmatxdesclist->CurTxDesc = descidx;


  /* disable the interrupt */
  //__disable_irq();
  //我最看不惯的就是关中断!!
  //dmatxdesclist->BuffersInUse += bd_count + 1U;


  /* Enable interrupts back */
  //__enable_irq();




  /* Return function status */
  return HAL_ETH_ERROR_NONE;
}




HAL_StatusTypeDef HAL_ETH_Transmit(ETH_HandleTypeDef *heth, ETH_TxPacketConfig *pTxConfig, uint32_t Timeout)
{
  uint32_t tickstart;
  const ETH_DMADescTypeDef *dmatxdesc;


  if(pTxConfig == NULL)
  {
    heth->ErrorCode |= HAL_ETH_ERROR_PARAM;
    return HAL_ERROR;
  }


  if(heth->gState == HAL_ETH_STATE_READY)
  {
    /* Config DMA Tx descriptor by Tx Packet info */
    if (ETH_Prepare_Tx_Descriptors(heth, pTxConfig, 0) != HAL_ETH_ERROR_NONE)
    {
      /* Set the ETH error code */
      heth->ErrorCode |= HAL_ETH_ERROR_BUSY;
      return HAL_ERROR;
    }


    dmatxdesc = (ETH_DMADescTypeDef *)(&heth->TxDescList)->TxDesc[heth->TxDescList.CurTxDesc];


    /* Incr current tx desc index */
    INCR_TX_DESC_INDEX(heth->TxDescList.CurTxDesc, 1U);


    /* Start transmission */
    /* issue a poll command to Tx DMA by writing address of next immediate free descriptor */
    //WRITE_REG(heth->Instance->DMACTDTPR, (uint32_t)(heth->TxDescList.TxDesc[heth->TxDescList.CurTxDesc]));
    __DMB();//修改!!
    WRITE_REG(heth->Instance->DMACTDTPR, ((uint32_t)(heth->Init.TxDesc + (uint32_t)(ETH_TX_DESC_CNT - 1))));


    tickstart = HAL_GetTick();


    /* Wait for data to be transmitted or timeout occurred */
    while((dmatxdesc->DESC3 & ETH_DMATXNDESCWBF_OWN) != (uint32_t)RESET)
    {
      if((heth->Instance->DMACSR & ETH_DMACSR_FBE) != (uint32_t)RESET)
      {
        heth->ErrorCode |= HAL_ETH_ERROR_DMA;
        heth->DMAErrorCode = heth->Instance->DMACSR;
        /* Set ETH HAL State to Ready */
        heth->gState = HAL_ETH_STATE_ERROR;
        /* Return function status */
        return HAL_ERROR;
      }


      /* Check for the Timeout */
      if(Timeout != HAL_MAX_DELAY)
      {
        if(((HAL_GetTick() - tickstart ) > Timeout) || (Timeout == 0U))
        {
          heth->ErrorCode |= HAL_ETH_ERROR_TIMEOUT;
          heth->gState = HAL_ETH_STATE_ERROR;
          return HAL_ERROR;
        }
      }
    }


    /* Return function status */
    return HAL_OK;
  }
  else
  {
    return HAL_ERROR;
  }
}


/**
  * @brief  Sends an Ethernet Packet in interrupt mode.
  * @param  heth: pointer to a ETH_HandleTypeDef structure that contains
  *         the configuration information for ETHERNET module
  * @param  pTxConfig: Hold the configuration of packet to be transmitted
  * @retval HAL status
  */
HAL_StatusTypeDef HAL_ETH_Transmit_IT(ETH_HandleTypeDef *heth, ETH_TxPacketConfig *pTxConfig)
{
  if(pTxConfig == NULL)
  {
    heth->ErrorCode |= HAL_ETH_ERROR_PARAM;
    return HAL_ERROR;
  }


  if(heth->gState == HAL_ETH_STATE_READY)
  {
    /* Config DMA Tx descriptor by Tx Packet info */
    if (ETH_Prepare_Tx_Descriptors(heth, pTxConfig, 1) != HAL_ETH_ERROR_NONE)
    {
      heth->ErrorCode |= HAL_ETH_ERROR_BUSY;
      return HAL_ERROR;
    }


    /* Incr current tx desc index */
    INCR_TX_DESC_INDEX(heth->TxDescList.CurTxDesc, 1U);


    __DMB();//修改!!


    /* Start transmission */
    /* issue a poll command to Tx DMA by writing address of next immediate free descriptor */
    //WRITE_REG(heth->Instance->DMACTDTPR, (uint32_t)(heth->TxDescList.TxDesc[heth->TxDescList.CurTxDesc]));
    WRITE_REG(heth->Instance->DMACTDTPR, (uint32_t)(heth->TxDescList.TxDesc[ETH_TX_DESC_CNT-1]));


    return HAL_OK;


  }
  else
  {
    return HAL_ERROR;
  }
}

接收的修改

接收相关的函数有2个被修改

uint8_t HAL_ETH_IsRxDataAvailable(ETH_HandleTypeDef *heth)
{
  ETH_RxDescListTypeDef *dmarxdesclist = &heth->RxDescList;
  uint32_t descidx = dmarxdesclist->CurRxDesc;
  ETH_DMADescTypeDef *dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];
  uint32_t descscancnt = 0;
  uint32_t appdesccnt = 0, firstappdescidx = 0;


  if(dmarxdesclist->AppDescNbr != 0U)
  {
    /* data already received by not yet processed*/
    return 0;
  }


  /* Check if descriptor is not owned by DMA */
  while((READ_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCWBF_OWN) == (uint32_t)RESET) && (descscancnt < (uint32_t)ETH_RX_DESC_CNT))
  {
    descscancnt++;


    /* Check if last descriptor */
    if(READ_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCWBF_LD) != (uint32_t)RESET)
    {
      /* Increment the number of descriptors to be passed to the application */
      appdesccnt += 1U;


      if(appdesccnt == 1U)
      {
        WRITE_REG(firstappdescidx, descidx);
      }


      /* Increment current rx descriptor index */
      INCR_RX_DESC_INDEX(descidx, 1U);


      /* Check for Context descriptor */
      /* Get current descriptor address */
      dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];


      if(READ_BIT(dmarxdesc->DESC3,  ETH_DMARXNDESCWBF_OWN)  == (uint32_t)RESET)
      {
        if(READ_BIT(dmarxdesc->DESC3,  ETH_DMARXNDESCWBF_CTXT)  != (uint32_t)RESET)
        {
          /* Increment the number of descriptors to be passed to the application */
          dmarxdesclist->AppContextDesc = 1;
          /* Increment current rx descriptor index */
          INCR_RX_DESC_INDEX(descidx, 1U);
        }
      }
      /* Fill information to Rx descriptors list */
      dmarxdesclist->CurRxDesc = descidx;
      dmarxdesclist->FirstAppDesc = firstappdescidx;
      dmarxdesclist->AppDescNbr = appdesccnt;


      /* Return function status */
      return 1;
    }
    /* Check if first descriptor */
    else if(READ_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCWBF_FD) != (uint32_t)RESET)
    {
      WRITE_REG(firstappdescidx, descidx);
      /* Increment the number of descriptors to be passed to the application */
      appdesccnt = 1U;


      /* Increment current rx descriptor index */
      INCR_RX_DESC_INDEX(descidx, 1U);
      /* Get current descriptor address */
      dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];
    }
    /* It should be an intermediate descriptor */
    else
    {
      /* Increment the number of descriptors to be passed to the application */
      appdesccnt += 1U;


      /* Increment current rx descriptor index */
      INCR_RX_DESC_INDEX(descidx, 1U);
      /* Get current descriptor address */
      dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];
    }
  }


  /* Build Descriptors if an incomplete Packet is received */
  if(appdesccnt > 0U)
  {
    dmarxdesclist->CurRxDesc = descidx;
    dmarxdesclist->FirstAppDesc = firstappdescidx;
    descidx = firstappdescidx;
    dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];


    for(descscancnt = 0; descscancnt < appdesccnt; descscancnt++)
    {
      WRITE_REG(dmarxdesc->DESC0, dmarxdesc->BackupAddr0);
      WRITE_REG(dmarxdesc->DESC3, ETH_DMARXNDESCRF_BUF1V);


      if (READ_REG(dmarxdesc->BackupAddr1) != ((uint32_t)RESET))
      {
        WRITE_REG(dmarxdesc->DESC2, dmarxdesc->BackupAddr1);
        SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_BUF2V);
      }


      SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_OWN);


      if(dmarxdesclist->ItMode != ((uint32_t)RESET))
      {
        SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_IOC);
      }
      if(descscancnt < (appdesccnt - 1U))
      {
        /* Increment rx descriptor index */
        INCR_RX_DESC_INDEX(descidx, 1U);
        /* Get descriptor address */
        dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descidx];
      }
    }


    /* Set the Tail pointer address to the last rx descriptor hold by the app */
    //WRITE_REG(heth->Instance->DMACRDTPR, (uint32_t)dmarxdesc);
  }


  /* Fill information to Rx descriptors list: No received Packet */
  dmarxdesclist->AppDescNbr = 0U;


  return 0;
}


HAL_StatusTypeDef HAL_ETH_BuildRxDescriptors(ETH_HandleTypeDef *heth)
{
  ETH_RxDescListTypeDef *dmarxdesclist = &heth->RxDescList;
  uint32_t descindex = dmarxdesclist->FirstAppDesc;
  __IO ETH_DMADescTypeDef *dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descindex];
  uint32_t totalappdescnbr = dmarxdesclist->AppDescNbr;
  uint32_t descscan;


  if(dmarxdesclist->AppDescNbr == 0U)
  {
    /* No Rx descriptors to build */
    return HAL_ERROR;
  }


  if(dmarxdesclist->AppContextDesc != 0U)
  {
    /* A context descriptor is available */
    totalappdescnbr += 1U;
  }


  for(descscan =0; descscan < totalappdescnbr; descscan++)
  {
    WRITE_REG(dmarxdesc->DESC0, dmarxdesc->BackupAddr0);
    WRITE_REG(dmarxdesc->DESC3, ETH_DMARXNDESCRF_BUF1V);


    if (READ_REG(dmarxdesc->BackupAddr1) != 0U)
    {
      WRITE_REG(dmarxdesc->DESC2, dmarxdesc->BackupAddr1);
      SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_BUF2V);
    }


    if(dmarxdesclist->ItMode != 0U){
      SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_IOC);
    }


    __DMB();//修改!!
    SET_BIT(dmarxdesc->DESC3, ETH_DMARXNDESCRF_OWN);


    if(descscan < (totalappdescnbr - 1U))
    {
      /* Increment rx descriptor index */
      INCR_RX_DESC_INDEX(descindex, 1U);
      /* Get descriptor address */
      dmarxdesc = (ETH_DMADescTypeDef *)dmarxdesclist->RxDesc[descindex];
    }
  }


  __DMB();//修改!!
  /* Set the Tail pointer address to the last rx descriptor hold by the app */
  //WRITE_REG(heth->Instance->DMACRDTPR, (uint32_t)dmarxdesc);//修改!!
  WRITE_REG(heth->Instance->DMACRDTPR, ((uint32_t)(heth->Init.RxDesc + (uint32_t)(ETH_RX_DESC_CNT - 1))));


  /* reset the Application desc number */
  WRITE_REG(dmarxdesclist->AppDescNbr, 0);


  /*  reset the application context descriptor */
  WRITE_REG(heth->RxDescList.AppContextDesc, 0);


  return HAL_OK;
}

其他修改

其实下面的修改无关紧要，因为它会在后面的传输中被修正，但强迫症不能忍啊。

static void ETH_DMATxDescListInit(ETH_HandleTypeDef *heth)
{
  ETH_DMADescTypeDef *dmatxdesc;
  uint32_t i;


  /* Fill each DMATxDesc descriptor with the right values */
  for(i=0; i < (uint32_t)ETH_TX_DESC_CNT; i++)
  {
    dmatxdesc = heth->Init.TxDesc + i;


    WRITE_REG(dmatxdesc->DESC0, 0x0);
    WRITE_REG(dmatxdesc->DESC1, 0x0);
    WRITE_REG(dmatxdesc->DESC2, 0x0);
    WRITE_REG(dmatxdesc->DESC3, 0x0);


    WRITE_REG(heth->TxDescList.TxDesc[i], (uint32_t)dmatxdesc);
  }


  heth->TxDescList.CurTxDesc = 0;


  /* Set Transmit Descriptor Ring Length */
  WRITE_REG(heth->Instance->DMACTDRLR, (ETH_TX_DESC_CNT -1));


  /* Set Transmit Descriptor List Address */
  WRITE_REG(heth->Instance->DMACTDLAR, (uint32_t) heth->Init.TxDesc);


  /* Set Transmit Descriptor Tail pointer *///修改!!
  WRITE_REG(heth->Instance->DMACTDTPR, ((uint32_t)(heth->Init.TxDesc + (uint32_t)(ETH_TX_DESC_CNT - 1))));//修改!!
}


/**
  * @brief  Initializes the DMA Rx descriptors in chain mode.
  *         called by HAL_ETH_Init() API.
  * @param  heth: pointer to a ETH_HandleTypeDef structure that contains
  *         the configuration information for ETHERNET module
  * @retval None
  */
static void ETH_DMARxDescListInit(ETH_HandleTypeDef *heth)
{
  ETH_DMADescTypeDef *dmarxdesc;
  uint32_t i;


  for(i = 0; i < (uint32_t)ETH_RX_DESC_CNT; i++)
  {
    dmarxdesc =  heth->Init.RxDesc + i;


    WRITE_REG(dmarxdesc->DESC0, 0x0);
    WRITE_REG(dmarxdesc->DESC1, 0x0);
    WRITE_REG(dmarxdesc->DESC2, 0x0);
    WRITE_REG(dmarxdesc->DESC3, 0x0);
    WRITE_REG(dmarxdesc->BackupAddr0, 0x0);
    WRITE_REG(dmarxdesc->BackupAddr1, 0x0);


    /* Set Rx descritors addresses */
    WRITE_REG(heth->RxDescList.RxDesc[i], (uint32_t)dmarxdesc);
  }


  WRITE_REG(heth->RxDescList.CurRxDesc, 0);
  WRITE_REG(heth->RxDescList.FirstAppDesc, 0);
  WRITE_REG(heth->RxDescList.AppDescNbr, 0);
  WRITE_REG(heth->RxDescList.ItMode, 0);
  WRITE_REG(heth->RxDescList.AppContextDesc, 0);


  /* Set Receive Descriptor Ring Length */
  WRITE_REG(heth->Instance->DMACRDRLR, ((uint32_t)(ETH_RX_DESC_CNT - 1)));


  /* Set Receive Descriptor List Address */
  WRITE_REG(heth->Instance->DMACRDLAR, (uint32_t) heth->Init.RxDesc);


  /* Set Receive Descriptor Tail pointer Address *///修改!!
  WRITE_REG(heth->Instance->DMACRDTPR, ((uint32_t)(heth->Init.RxDesc + (uint32_t)(ETH_RX_DESC_CNT - 1))));//修改!!
}