F4_HAL/i2c: Move DMA set-up to after sending I2C address.

Previous to this patch the DMA was set-up and then the I2C address sent.
If the I2C address sending failed (eg no I2C device on the bus) then the
DMA was left in an inconsistent state.

This patch moves the DMA setup to after a successful sending of the I2C
address(es).

Author: dpgeorge

STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_i2c.c

@@ -2999,21 +2999,6 @@ HAL_StatusTypeDef HAL_I2C_Mem_Write_DMA(I2C_HandleTypeDef *hi2c, uint16_t DevAdd
 
     if(hi2c->XferSize > 0U)
     {
-      /* Set the I2C DMA transfer complete callback */
-      hi2c->hdmatx->XferCpltCallback = I2C_DMAXferCplt;
-
-      /* Set the DMA error callback */
-      hi2c->hdmatx->XferErrorCallback = I2C_DMAError;
-
-      /* Set the unused DMA callbacks to NULL */
-      hi2c->hdmatx->XferHalfCpltCallback = NULL;
-      hi2c->hdmatx->XferM1CpltCallback = NULL;
-      hi2c->hdmatx->XferM1HalfCpltCallback = NULL;
-      hi2c->hdmatx->XferAbortCallback = NULL;
-
-      /* Enable the DMA Stream */
-      HAL_DMA_Start_IT(hi2c->hdmatx, (uint32_t)hi2c->pBuffPtr, (uint32_t)&hi2c->Instance->DR, hi2c->XferSize);
-
       /* Send Slave Address and Memory Address */
       if(I2C_RequestMemoryWrite(hi2c, DevAddress, MemAddress, MemAddSize, I2C_TIMEOUT_FLAG, tickstart) != HAL_OK)
       {
@@ -3031,6 +3016,23 @@ HAL_StatusTypeDef HAL_I2C_Mem_Write_DMA(I2C_HandleTypeDef *hi2c, uint16_t DevAdd
         }
       }
 
+      /* dpgeorge: DMA initialisation is moved to after sending the address */
+
+      /* Set the I2C DMA transfer complete callback */
+      hi2c->hdmatx->XferCpltCallback = I2C_DMAXferCplt;
+
+      /* Set the DMA error callback */
+      hi2c->hdmatx->XferErrorCallback = I2C_DMAError;
+
+      /* Set the unused DMA callbacks to NULL */
+      hi2c->hdmatx->XferHalfCpltCallback = NULL;
+      hi2c->hdmatx->XferM1CpltCallback = NULL;
+      hi2c->hdmatx->XferM1HalfCpltCallback = NULL;
+      hi2c->hdmatx->XferAbortCallback = NULL;
+
+      /* Enable the DMA Stream */
+      HAL_DMA_Start_IT(hi2c->hdmatx, (uint32_t)pData, (uint32_t)&hi2c->Instance->DR, Size);
+
       /* Clear ADDR flag */
       __HAL_I2C_CLEAR_ADDRFLAG(hi2c);
 
@@ -3120,21 +3122,6 @@ HAL_StatusTypeDef HAL_I2C_Mem_Read_DMA(I2C_HandleTypeDef *hi2c, uint16_t DevAddr
 
     if(hi2c->XferSize > 0U)
     {
-      /* Set the I2C DMA transfer complete callback */
-      hi2c->hdmarx->XferCpltCallback = I2C_DMAXferCplt;
-
-      /* Set the DMA error callback */
-      hi2c->hdmarx->XferErrorCallback = I2C_DMAError;
-
-      /* Set the unused DMA callbacks to NULL */
-      hi2c->hdmarx->XferHalfCpltCallback = NULL;
-      hi2c->hdmarx->XferM1CpltCallback = NULL;
-      hi2c->hdmarx->XferM1HalfCpltCallback = NULL;
-      hi2c->hdmarx->XferAbortCallback = NULL;
-
-      /* Enable the DMA Stream */
-      HAL_DMA_Start_IT(hi2c->hdmarx, (uint32_t)&hi2c->Instance->DR, (uint32_t)hi2c->pBuffPtr, hi2c->XferSize);
-
       /* Send Slave Address and Memory Address */
       if(I2C_RequestMemoryRead(hi2c, DevAddress, MemAddress, MemAddSize, I2C_TIMEOUT_FLAG, tickstart) != HAL_OK)
       {
@@ -3152,6 +3139,21 @@ HAL_StatusTypeDef HAL_I2C_Mem_Read_DMA(I2C_HandleTypeDef *hi2c, uint16_t DevAddr
         }
       }
 
+      /* Set the I2C DMA transfer complete callback */
+      hi2c->hdmarx->XferCpltCallback = I2C_DMAXferCplt;
+
+      /* Set the DMA error callback */
+      hi2c->hdmarx->XferErrorCallback = I2C_DMAError;
+
+      /* Set the unused DMA callbacks to NULL */
+      hi2c->hdmarx->XferHalfCpltCallback = NULL;
+      hi2c->hdmarx->XferM1CpltCallback = NULL;
+      hi2c->hdmarx->XferM1HalfCpltCallback = NULL;
+      hi2c->hdmarx->XferAbortCallback = NULL;
+
+      /* Enable the DMA Stream */
+      HAL_DMA_Start_IT(hi2c->hdmarx, (uint32_t)&hi2c->Instance->DR, (uint32_t)pData, Size);
+
       if(Size == 1U)
       {
         /* Disable Acknowledge */