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DMA promblem on iq80321 redboot


Hi all,
  I am new to reboot and  working  on a iq80321 board. I made a simple test about a memory to memory DMA on redboot.
To copy 64 bytes 
form 0x830000(redboot virtue address,physical address is 0xa0830000),
to 0x840000(redboot virtue address,physical address is 0xa0840000),
the DMA discriptor at 0x800000(redboot virtue address,physical address is 0xa0800000)
what I did is  filling  the  DMA Chain Descriptors at DDR RAM as the following,

mfill -b 0xffffe400 -l 4 -p 0  //clear CSR0

mfill -b 0x800000 -l 4 -p 0    //Next Descriptor Address is 0
mfill -b 0x800004 -l 4 -p 0xa0830000 //source physical Address
mfill -b 0x80000c -l 4 -p 0xa0840000 //destination physical address
mfill -b 0x800010 -l 4 -p 0x40   //DMA count 64 bytes
mfill -b 0x80001c -l 4 -p 0x5e   //memory to memory ,interrupt enable

mfill -b 0xffffe410 -l 4 -p 0xa0800000  //write the DAR,0xa0800000 is the physical address of the DMA Chain Descriptors
mfill -b 0xffffe400 -l 4 -p 1 //write 1 to CSR0,start DMA

but it didn't work ,No data was transfered. But I could get right result using bdi2000,not loading redboot. 
I am puzzled. What should i do?  Any suggestion will be of great help. 

Lucy
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