HAL库摄像头DCMI—DMA配置后，屏幕只显示一半是怎么回事啊？

DCMI配置如下所示：

void DCMI_Init(void)
{
    __HAL_RCC_DCMI_CLK_ENABLE();

    DCMI_Handle.Instance              = DCMI;   
    DCMI_Handle.Init.SynchroMode      = DCMI_SYNCHRO_HARDWARE;
    DCMI_Handle.Init.PCKPolarity      = DCMI_PCKPOLARITY_RISING;
    DCMI_Handle.Init.VSPolarity       = DCMI_VSPOLARITY_LOW;
    DCMI_Handle.Init.HSPolarity       = DCMI_HSPOLARITY_LOW;
    DCMI_Handle.Init.CaptureRate      = DCMI_CR_ALL_FRAME;
    DCMI_Handle.Init.ExtendedDataMode = DCMI_EXTEND_DATA_8B;
    HAL_DCMI_Init( DCMI_Handle);     

    HAL_NVIC_SetPriority(DCMI_IRQn, 5, 0);
    HAL_NVIC_EnableIRQ(DCMI_IRQn);     
   
}
DMA配置如下：

void OV2640_DMA_Config(uint32_t DMA_Memory0BaseAddr,uint32_t DMA_BufferSize)
{

  __HAL_RCC_DMA2_CLK_ENABLE();
    __HAL_LINKDMA( DCMI_Handle, DMA_Handle, DMA_Handle_dcmi);
   
  DMA_Handle_dcmi.Instance = DMA2_Stream1;
  DMA_Handle_dcmi.Init.Channel = DMA_CHANNEL_1;  
  DMA_Handle_dcmi.Init.Direction = DMA_PERIPH_TO_MEMORY;
  DMA_Handle_dcmi.Init.PeriphInc = DMA_PINC_DISABLE;
  DMA_Handle_dcmi.Init.MemInc = DMA_MINC_ENABLE;           
  DMA_Handle_dcmi.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;
  DMA_Handle_dcmi.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;
  DMA_Handle_dcmi.Init.Mode = DMA_CIRCULAR;                              
  DMA_Handle_dcmi.Init.Priority = DMA_PRIORITY_HIGH;
  DMA_Handle_dcmi.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
  DMA_Handle_dcmi.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
  DMA_Handle_dcmi.Init.MemBurst = DMA_MBURST_INC8;
  DMA_Handle_dcmi.Init.PeriphBurst = DMA_PBURST_SINGLE;
  HAL_DMA_Init( DMA_Handle_dcmi);
  
  HAL_NVIC_SetPriority(DMA2_Stream1_IRQn, 5, 0);
  HAL_NVIC_EnableIRQ(DMA2_Stream1_IRQn);
  
  HAL_DCMI_Start_DMA( DCMI_Handle, DCMI_MODE_CONTINUOUS, (uint32_t)DMA_Memory0BaseAddr,DMA_BufferSize);
  
}

主函数调用
DCMI_Init()
OV2640_DMA_Config(LCD_FB_START_ADDRESS,LCD_GetXSize()*LCD_GetYSize()/2);
LCD_FB_START_ADDRESS为LCD显存首地址，LCD_GetXSize()*LCD_GetYSize()/2为像素个数
屏幕只显示一半是怎么回事啊？？代码哪里出了问题？？