TMS320F28377D: SPI和dma配合使用，传输结束rx fifo总是会留有2个数据DMA没有传输，怎么能让spiRX fifo中的数据全部传输完成。

spi配置

SpibRegs.SPICCR.bit.SPISWRESET = 0;
SpibRegs.SPICCR.all = 0x004F; 

SpibRegs.SPICTL.all = 0x0006; 
SpibRegs.SPISTS.all = 0x0000; 
SpibRegs.SPIBRR.all= 0x0001;

//增加FIFO
SpibRegs.SPIFFTX.all =0xE040 ;
SpibRegs.SPIFFRX.all =0x2040 ;

SpibRegs.SPIFFTX.bit.TXFFIL = 1; // Set TX FIFO level
SpibRegs.SPIFFRX.bit.RXFFIL = 1; // Set TX FIFO level

SpibRegs.SPIPRI.bit.FREE = 1;
SpibRegs.SPICCR.bit.SPISWRESET = 1;

dma 配置

DMACH5AddrConfig((volatile UINT16*)(&SpibRegs.SPITXBUF),(volatile UINT16 *)m_u16DmaTxData);
DMACH5BurstConfig(0,1,0); // Burst size, src step, dest step
DMACH5TransferConfig(1,1,0); // transfer size, src step, dest step

DMACH5ModeConfig(DMA_SPIBTX,PERINT_ENABLE,ONESHOT_ENABLE,CONT_DISABLE,
SYNC_DISABLE,SYNC_SRC,OVRFLOW_DISABLE,SIXTEEN_BIT,
CHINT_END,CHINT_ENABLE);

DMACH6AddrConfig((volatile UINT16*)m_u16DmaTxData,(volatile UINT16 *)(&SpibRegs.SPIRXBUF));
DMACH6BurstConfig(0,0,1); // Burst size, src step, dest step
DMACH6TransferConfig(1,0,1); // transfer size, src step, dest step

DMACH6ModeConfig(DMA_SPIBRX,PERINT_ENABLE,ONESHOT_ENABLE,CONT_DISABLE,
SYNC_DISABLE,SYNC_SRC,OVRFLOW_DISABLE,SIXTEEN_BIT,
CHINT_END,CHINT_ENABLE);

在dma传输结束后，RX_FIFO中总是发现有两个（SPIFFRX.bit.RXFFST =2）没传出，请问有什么办法让dma把RX_FIFO中的数据都读出来。