c6748 UART and SPI using EDMA simultaneously

hello:

I am now using C6748, and I want to using UART to send data by EDMA,and SPI to write or read from SPI flash by EDMA at the same time.

Now I do it, But it does not work correctly，they can work for a while , and then the uart can not send data and the SPI  can not  write or read from SPI flash.

The UART and SPI flash use the same EDMA interrupt hander function. And the EDMA register EMR ,SECR,IPR show that there are UART and SPI events missing,and IPR 

show   the uart and SPI channel not clear. Actually， I really clear the IPR in the EDMA interrupt function. 

I dont't know why the events miss and IPR not clear! Can anyone help me? 

Best Regards