DM6437 SPI problem

I am programming on using SPI function, the master device is NXP ARM chip and slave is DM6437. I configured the SPI word length as 16bit and set CLKGDV = 0.

The master device sends the bytes from 0x0000 to 0x03E8 by a for loop, the received result of DM6437(slave) is correct if master's data rate under 4 Mbit / Sec.

It will be lost some data when I set data rate above 4 Mbit / Sec on master, does the SPI data rate of DM6437 on slave mode able to over 4 Mbit / Sec ?

My SPI initial function :

Int16 EVMDM6437_SPI_Init ( )

{

      MCBSP0_SPCR &= ~(1 << 16) ;    // XRST

      MCBSP0_SPCR &= ~(1 << 0) ;      // RRST

      MCBSP0_SPCR &= ~(1 << 22) ;   // GRST

      MCBSP0_SPCR = ( 2 << 11 ) ;        // CLKSTP = 2h

      MCBSP0_PCR = ( 1 << 3 ) ;            // FSXP = 1

      MCBSP0_SRGR = ( 1 << 29 ) ;      // CLKSM = 1 , CLKGDV = 0

      MCBSP0_XCR = (  2 << 5 ) ;           // transmit word length = 16 bit

      MCBSP0_RCR = ( 2 << 5 ) ;          // receipt word length = 16 bit

      MCBSP0_SPCR |= ( 1 << 22 ) ;   // GRST

      delay( ) ;

      MCBSP0_SPCR |= ( 1 << 0 ) ;     // RRST

      return ;

}