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Unable to initiate DMA transfer

Altera_Forum
Honored Contributor II
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Hi, 

 

I am using a Stratix IV PCIe HardIP and have a contiguous buffer DMA along with it. 

 

The BAR0 Address Map to a onchip memory location is 0x200000 to 0x200fff (64bit) 

 

BAR2 connects to the DMA Control register: 0x4000 to 0x403f. (32bit) 

The Read master and write master of the DMA are connected to the txs of the PCIe bus. 

 

I am trying using a simple 32bit transaction for a bunch of address from the DMA buffer to the memory but am unable to get it working. 

Setup: 

Besides the FPGA setup mentioned above. 

 

It uses a simple Windriver, 

See attached jpg for an example: 

https://www.alteraforum.com/forum/attachment.php?attachmentid=6485  

 

but everytime I write to the BAR2 DMA offset 0x4001 with the start address and read back with e.g. 0x200000 

as a 32bit (non block transfer)  

I am not able to add a source address it essentially reads back as zero. 

 

The same is applicable for the write register as well as the control register. 

 

I am using a s4gx_gen1x8_qsys reference model. So there are no changes essentially to my model. 

 

i) What is wrong with my method of access to the DMA? 

 

ii) Since I am transfering from my PC, what do I provide as a source address for in the source address register? 

 

iii) the PCIE:txs handles the write, so for the write address to the on chip memory do I use 0x200000 of BAR0 or should I connect it through another bus internally to the DMA with a separate address? 

 

Thanks
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