Hi all,
I need some help in EDMA transfer from AEMIF to DDR memory on DM6446.
Details:
I have a FPGA(16 bit interface) connected to AEMIF(CS4). I have to read
5 times, 500 words(16bit) each from my application. I have written a small char
driver
to do the DMA read operation.
Problem:
DMA transfer is done for first 500 words and from next time onwards DMA
transfer will miss
the data in chunks ok 16 or 32 words. i.e say I have application code -
/**********application code **********/
- Open the device then
for(i=0;i<5;i++)
{
read(fd, buff, 500*2); //DMA read call
Print the buffer
}
memcpy to global buffer and send to host PC via USB
/********************/
For i = 0; I will get the data from FPGA correctly, from i=1 onwards, data will
be missed not entire 500words but in chunks of 16/32 words
As I have also registered the callback, I am getting completion interrupt for
the everytime!
/*********Configurations and driver code*************/
#define FIFO 0x06000000;
unsigned short *psr = (unsigned short *)FIFO;
unsigned short *pdt = NULL;
unsigned short *pdtPhy = NULL;
acnt = 2; (16bit)
bcnt = 500;
ccnt = 1;
Device_read(...)
{
pdt = (uint16_t*) kmalloc(500*2, GFP_KERNEL);
pdtPhy = virt_to_phys(pdt);
// initialise DMA
if (davinci_request_dma(0, "DMATEST", davinci_edma_cb, NULL, &ch,
&tcc, EVENTQ_0))
{
return -1;
}
// set DMA parameters
davinci_set_dma_dest_params(ch, pdtPhy, INCR, 0);
davinci_set_dma_src_params(ch, psr, INCR, 0);
davinci_set_dma_src_index(ch, 0, 0); // args: srcbidx srccidx
davinci_set_dma_dest_index(ch, acnt, 0); // args: destbidx,
destcidx
davinci_set_dma_transfer_params(ch, acnt, bcnt, ccnt, 0, ABSYNC);
// args: acnt, bcnt, ccnt, bcntrld, sync_mode
// start DMA transfer
davinci_start_dma(ch);
copy_to_user(from Local buffer to User buffer);
davinci_request_dma(ch);
}
/********************/
Do you think I have missed any configurations or is there a know problem with
the driver?
Note:
Also tried to move the Request Dma Channel to OPEN method and Free Dma Channel
to CLOSE method.
Still no luck!
Thanks and Regards,
Nitin Joshi
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