Guys, I have a desperate problem on my hand. Using DMA to do burst transfers from DDR to on-chip RAM. Using the reference code as shown below. Searched all the forums and confirmed people using the same NIOS code and succesfully making the transfer. Please help Code: int main() { int i,rc; unsigned int On_chip_SRAM_base_dma= 0x41030000; unsigned int DDR_write_OFFSET_ADDRESS_dma=0x00000500; int data_dma[4]={2882343476,4020983416, 9867509251, 6945207616}; unsigned long *sram_ptr2=(unsigned short*)On_chip_SRAM_base_dma; printf("Hello from Nios II!\n"); printf("Testing DMA transfer from DDR to SRAM\n"); for (i=0;i<4;i++){ IOWR(ALTMEMDDR_BASE,DDR_write_OFFSET_ADDRESS_dma + i, data_dma); printf("data: %08x is correctly written to memory offset on ddr: %08x \n",data_dma,DDR_write_OFFSET_ADDRESS_dma+i); } for(i=0;i<4;i++){ read_data1=iord(altmemddr_base,ddr_write_offset_address_dma+i); printf("read %08x from address %08x on ddr\n",read_data1,(DDR_write_OFFSET_ADDRESS_dma+ i)); } // DMA code alt_dma_txchan txchan; alt_dma_rxchan rxchan; void *tx_data= (void*)DDR_write_OFFSET_ADDRESS_dma; void *rx_buffer= (void*)On_chip_SRAM_base_dma; /* Create the transmit channel */ if ((txchan = alt_dma_txchan_open("/dev/dma_0")) == NULL) { printf ("Failed to open transmit channel\n"); exit (1); } else { printf("Transmit channel setup successful\n"); } /* Create the receive channel */ if ((rxchan = alt_dma_rxchan_open("/dev/dma_0")) == NULL) { printf ("Failed to open receive channel\n"); exit (1); } else { printf("Receive channel setup successful\n"); } /* Post the transmit request */ if ((rc = alt_dma_txchan_send (txchan, tx_data, 4 ,NULL , NULL)) < 0) { printf ("Failed to post transmit request, reason = %i\n", rc); exit (1); } /* Post the receive request */ if ((rc = alt_dma_rxchan_prepare (rxchan, rx_buffer , 4, done, NULL)) < 0) { printf ("Failed to post read request, reason = %i\n", rc); exit (1); } /*while(1){ unsigned int status[32]= IOWR_ALTERA_AVALON_DMA_STATUS(0x41000000,0X00); if(status[0]=1){ prontf("VIOLA!!"); break; } } /* wait for transfer to complete */ while (!rx_done); printf ("Transfer successful!\n"); alt_dma_rxchan_close ("/dev/dma_0"); alt_dma_txchan_close ("/dev/dma_0"); //sram_ptr=On_chip_SRAM_base_dma; for(i=0;i<4;i++){ read_data3=*sram_ptr2; printf("read %08x from address %08x ,read_data3,(On_chip_SRAM_base_dma+ i)); sram_ptr2++; } The results: Hello from Nios II! Testing DMA transfer from DDR to SRAM Data: abcd1234 is correctly written to memory offset on DDR: 00000500 Data: efab5678 is correctly written to memory offset on DDR: 00000501 Data: 4c263e03 is correctly written to memory offset on DDR: 00000502 Data: 9df77540 is correctly written to memory offset on DDR: 00000503 Read abcd1234 from address 00000500 on DDR Read efab5678 from address 00000501 on DDR Read 4c263e03 from address 00000502 on DDR Read 9df77540 from address 00000503 on DDR Transmit channel setup successful Receive channel setup successful Transfer successful! Read 08080808 from address 41030000 //WORING RESULTS!:( Read 00000000 from address 41030001 Read 00000000 from address 41030002 Read 00000000 from address 41030003 Altera Gurus, Please come to the rescue!!!!!!!! Many Thanks. Appreciate your response!

I would use IORD to readback the destination buffer to make sure you are not reading back cached data. Also the transfer length is in bytes so if you want to move 16 bytes worth of data pass in '16' instead of '4' to the rx and tx calls.

Yeah, I am using 16 for 16 bytes transfer. In the code I posted I was just trying for 1 word transfer. And with IORD also , it doesn't work.:(.Anyone else has a clue please???? Looks such a small straight forward thing. Can't figure out what is wrong!!!!!!!!!!!!

Could it be a problem with memory width? Why do you use the 'unsigned short' cast? (unsigned short*)On_chip_SRAM_base_dma; Is onchip ram 16-bit or 32-bit wide?

Nope. I changed that to (long*). Was hoping for something different. BUT No luck there as well.:(

Forum Discussion

Altera_Forum

Honored Contributor

14 years ago

Serious Problem with DMA transfer.

Guys,

I have a desperate problem on my hand. Using DMA to do burst transfers from DDR to on-chip RAM. Using the reference code as shown below. Searched all the forums and confirmed people using the same NIOS code and succesfully making the transfer.

Please help

Code:

int main()

{

int i,rc;

unsigned int On_chip_SRAM_base_dma= 0x41030000;

unsigned int DDR_write_OFFSET_ADDRESS_dma=0x00000500;

int data_dma[4]={2882343476,4020983416, 9867509251, 6945207616};

unsigned long *sram_ptr2=(unsigned short*)On_chip_SRAM_base_dma;

printf("Hello from Nios II!\n");

printf("Testing DMA transfer from DDR to SRAM\n");

for (i=0;i<4;i++){

IOWR(ALTMEMDDR_BASE,DDR_write_OFFSET_ADDRESS_dma + i, data_dma);

printf("data: %08x is correctly written to memory offset on ddr: %08x \n",data_dma,DDR_write_OFFSET_ADDRESS_dma+i);

}

for(i=0;i<4;i++){

read_data1=iord(altmemddr_base,ddr_write_offset_address_dma+i);

printf("read %08x from address %08x on ddr\n",read_data1,(DDR_write_OFFSET_ADDRESS_dma+ i));

}

// DMA code

alt_dma_txchan txchan;

alt_dma_rxchan rxchan;

void *tx_data= (void*)DDR_write_OFFSET_ADDRESS_dma;

void *rx_buffer= (void*)On_chip_SRAM_base_dma;

/* Create the transmit channel */

if ((txchan = alt_dma_txchan_open("/dev/dma_0")) == NULL)

{

printf ("Failed to open transmit channel\n");

exit (1);

}

else

{

printf("Transmit channel setup successful\n");

}

/* Create the receive channel */

if ((rxchan = alt_dma_rxchan_open("/dev/dma_0")) == NULL)

{

printf ("Failed to open receive channel\n");

exit (1);

}

else

{

printf("Receive channel setup successful\n");

}

/* Post the transmit request */

if ((rc = alt_dma_txchan_send (txchan, tx_data, 4 ,NULL , NULL)) < 0)

{

printf ("Failed to post transmit request, reason = %i\n", rc);

exit (1);

}

/* Post the receive request */

if ((rc = alt_dma_rxchan_prepare (rxchan, rx_buffer , 4, done, NULL)) < 0)

{

printf ("Failed to post read request, reason = %i\n", rc);

exit (1);

}

/*while(1){

unsigned int status[32]= IOWR_ALTERA_AVALON_DMA_STATUS(0x41000000,0X00);

if(status[0]=1){

prontf("VIOLA!!");

break;

}

/* wait for transfer to complete */

while (!rx_done);

printf ("Transfer successful!\n");

alt_dma_rxchan_close ("/dev/dma_0");

alt_dma_txchan_close ("/dev/dma_0");

//sram_ptr=On_chip_SRAM_base_dma;

for(i=0;i<4;i++){

read_data3=*sram_ptr2;

printf("read %08x from address %08x ,read_data3,(On_chip_SRAM_base_dma+ i));

sram_ptr2++;

}

The results:

Hello from Nios II!

Testing DMA transfer from DDR to SRAM

Data: abcd1234 is correctly written to memory offset on DDR: 00000500

Data: efab5678 is correctly written to memory offset on DDR: 00000501

Data: 4c263e03 is correctly written to memory offset on DDR: 00000502

Data: 9df77540 is correctly written to memory offset on DDR: 00000503

Read abcd1234 from address 00000500 on DDR

Read efab5678 from address 00000501 on DDR

Read 4c263e03 from address 00000502 on DDR

Read 9df77540 from address 00000503 on DDR

Transmit channel setup successful

Receive channel setup successful

Transfer successful!

Read 08080808 from address 41030000 //WORING RESULTS!:(

Read 00000000 from address 41030001

Read 00000000 from address 41030002

Read 00000000 from address 41030003

Altera Gurus, Please come to the rescue!!!!!!!!

Many Thanks.

Appreciate your response!

11 Replies

Altera_Forum
Honored Contributor
14 years ago
In the above code i was testing for just a word transfer(4 bytes) . When I tried transferring 16 bytes, the 00000000s in the result changed as follows:

Hello from Nios II!

Testing DMA transfer from DDR to SRAM

Data: abcd1234 is correctly written to memory offset on DDR: 00000500
Data: efab5678 is correctly written to memory offset on DDR: 00000501
Data: 4c263e03 is correctly written to memory offset on DDR: 00000502
Data: 9df77540 is correctly written to memory offset on DDR: 00000503

Read abcd1234 from address 00000500 on DDR
Read efab5678 from address 00000501 on DDR
Read 4c263e03 from address 00000502 on DDR
Read 9df77540 from address 00000503 on DDR

Transmit channel setup successful
Receive channel setup successful
Transfer successful!

Read 08080808 from address 41030000 //WroNG RESULTS!:(
Read 7665642f from address 41030001
Read 7665642f from address 41030002
Read 61746a2f from address 41030003

But still wrong results!:(:(:(

Many Thanks.
Appreciate your response!
Altera_Forum
Honored Contributor
14 years ago
I would use IORD to readback the destination buffer to make sure you are not reading back cached data. Also the transfer length is in bytes so if you want to move 16 bytes worth of data pass in '16' instead of '4' to the rx and tx calls.
Altera_Forum
Honored Contributor
14 years ago
Yeah, I am using 16 for 16 bytes transfer. In the code I posted I was just trying for 1 word transfer. And with IORD also , it doesn't work.:(.Anyone else has a clue please????
Looks such a small straight forward thing. Can't figure out what is wrong!!!!!!!!!!!!
Altera_Forum
Honored Contributor
14 years ago
Could it be a problem with memory width?
Why do you use the 'unsigned short' cast?
(unsigned short*)On_chip_SRAM_base_dma;
Is onchip ram 16-bit or 32-bit wide?
Altera_Forum
Honored Contributor
14 years ago
Nope. I changed that to (long*). Was hoping for something different. BUT No luck there as well.:(
Altera_Forum
Honored Contributor
14 years ago
Which memory are you running your code from? Make sure it's not in one of those memories you are storing test data or the destination. If you are randomly picking locations which also host your code you might be clobbering your software.
Altera_Forum
Honored Contributor
14 years ago
@BadOmen.. The DE3 board I am using does not have an on-board SRAM. So I ma assuming that the NIOS code is stored on the on-chip memory which is also my destination. I thought of it, but how do i figure out which locations exactly does my NIOS code occupy??
Many thanks for your reply. really appreciate it!:)
Altera_Forum
Honored Contributor
14 years ago
Your code footprint will change if you breath on it so instead of finding a spot that is not occupied I would do one of the following instead:

Pre-allocate your buffer so that the compiler will not attempt to place anything there
Dynamically allocate your buffer at run time

I like# 1 better and there are different ways to do it. # 2 is just use malloc or something similar to allocate a memory. The reason why I don't like# 2 is that allocating memory at run time should be avoided (if possible) since if you run out of memory that might be hard to debug.

So back to# 1.... You can write your own linker script and declare a region of the memory to hold your buffer and just make sure the linker doesn't attempt to place any code/data there during the linking stage. Or if you know what your buffer size is going to be ahead of time you could just declare an array in your code and use that array as the destination.

Before kicking off the DMA you should make sure your source or destination buffers are not cached. There are many ways to do that so I'll let you search around for that or just read the documentation about the Nios II data cache.
Altera_Forum
Honored Contributor
14 years ago
SO I DID WHAT YOU SAID. INITIALIZED AN ARRAY AND USED IT TO STORE THE VALUES T MAKE SURE CODE AND DATA DONT OVE
LAP AS FOLLOWS:

volatile static int rx_done = 0;

static void done_DMA(void* handle, void* data)
{
rx_done = 1;
printf("Thanks Jeez\n");
}

int main(int argc, char* argv[], char* envp[])
{
int rc,i;

long data_dma[4]={0xAAAAAAAA,0xABCD1234, 0x12345678, 0x945207616};
unsigned long DDR_write_OFFSET_ADDRESS_dma=0x03000000;
unsigned long read_data1[4],read_data3[4];

for (i=0;i<4;i++){
IOWR(ALTMEMDDR_BASE,DDR_write_OFFSET_ADDRESS_dma + i, data_dma);
printf("data %08x is correctly written to memory offset %08x on ddr\n",data_dma,DDR_write_OFFSET_ADDRESS_dma+4*i);
}
for(i=0;i<4;i++){
read_data1=iord(altmemddr_base,ddr_write_offset_address_dma+i);
printf("read %08x from address %08x on ddr\n",read_data1,(DDR_write_OFFSET_ADDRESS_dma+ 4*i));
}

//DMA opeartion

alt_dma_txchan txchan;
alt_dma_rxchan rxchan;

unsigned long* tx_data = (unsigned long*)DDR_write_OFFSET_ADDRESS_dma ;// pointer to data to send

unsigned long* rx_buffer = (unsigned long*) read_data3;

printf("\n\nTesting DMA transfer from DDR to SRAM\n\n");

alt_dcache_flush_all();

// // Create the transmit channel
if ((txchan = alt_dma_txchan_open("/dev/dma_0")) == NULL)
{
printf ("Failed to open transmit channel\n");
exit (1);
}

// Create the receive channel
if ((rxchan = alt_dma_rxchan_open("/dev/dma_0")) == NULL)
{
printf ("Failed to open receive channel\n");
exit (1);
}

if(alt_dma_txchan_ioctl(txchan,ALT_DMA_SET_MODE_32,NULL)<0)
{
exit(1);
}

if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_SET_MODE_32,NULL)<0)
{
exit(1);
}

if(alt_dma_txchan_ioctl(txchan,ALT_DMA_TX_ONLY_OFF,NULL)<0)
{
exit(1);
}

if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_RX_ONLY_OFF,NULL)<0)
{
exit(1);
}

// Post the transmit request
if ((rc = alt_dma_txchan_send (txchan,tx_data,16,NULL,NULL)) < 0)
{
printf ("Failed to post transmit request, reason = %i\n", rc);
exit (1);
}

// Post the receive request
if ((rc = alt_dma_rxchan_prepare (rxchan,rx_buffer,16,done_DMA,NULL)) < 0)
{
printf ("Failed to post read request, reason = %i\n", rc);
exit (1);
}

// wait for transfer to complete
while (!rx_done);
printf ("Transfer successful!\n\n");

for(i=0;i<4;i++){

printf("Read %08x from address %08x \n",read_data3,&read_data3);

}

return 0;

}

Results:

Read 00000001 from address 3fffffd0
Read 000001ff from address 3fffffd4
Read 3fffffec from address 3fffffd8
Read deadbeef from address 3fffffdc //DEADBEEF!! what the heck??

Still not working Badomen!! :(
Altera_Forum
Honored Contributor
14 years ago
Any suggestions people? Still stuck. Fr transferring 16 bytes of burst, even tried using something as:
alt_dcache_flush_all();

&

tx_data = (void*)alt_uncached_malloc(0x10);
rx_buffer = (void*)alt_uncached_malloc(0x10);

to make sure there are no data cache problems.
Suggestions please.........

Forum Discussion

Serious Problem with DMA transfer.

11 Replies

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