cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
Participant
Participant
377 Views
Registered: ‎01-27-2017

PCIe XDMA bypass 64-bit access issues

Vivado Version: 2020.1
Device Family : kintex7 on KC705.
Name of the IP: DMA/Bridge Subsystem for PCI Express - DMA mode - Configured as following
- PCIe Gen2 x4, AXI Data Width 64
- PCIe to DMA (64-bit Enable, Prefetable),
- PCIe to DMA Bypass (64-bit Enable, Size 2GB

 

Hello Xilinx community,

I am facing an issue when issuing 64-bit Read Write Access on AXI Bypass interface on our KC705 development board

  • During a 64-bit write access at offset 0x0: AXI bypass interface is generating 1 32-bit write access
    • awsize = 8-bytes
    • wstrb= 0x0F
    • wdata[31:0] consistent, wdata[63:32] Not consistent
    • Thus, something wrong happened
  • During a 64-bit write access at offset 0x4: AXI bypass interface is generating 2 32-bit write access
    • for 1st AXI bypass Access
      • awsize = 4-bytes
      • wstrb= 0xF0
      • wdata[63:32] consistent
    • for 2nd AXI bypass Access
      • awsize = 4-bytes
      • wstrb= 0x0F
      • wdata[31:00] consistent
    •  Thus, everything is fine
  • During a 64-bit read access, whatever the offset, the returned value by the driver is 0xFFFFFFFFFFFFFFFF
    • but 2 32-bit read access are returning the correct value
  • All others 8-bit,16-bit,32-bit accesses are working well.

We have executed the same SW Application on "DMA/Bridge Subsystem for PCI Express - DMA mode" on Virtex7 Ultrascale in PCIe Gen3 Mode and no bug have been found.

Can you please confirm there is a problem and if yes, is there anyway to solve it?

Best Regards,

Xavier

0 Kudos
4 Replies
Highlighted
Newbie
Newbie
251 Views
Registered: ‎08-13-2020

Hi Xavier,

try 1MB address space on the DMA bypass.

I had also problems when I use 64bit enabled and another address space than 1MB.

Without 64bit, I checked address spaces from 256kB to 16MB, all was fine.

The return value 0xFFFF... is a errornous AXI access.

 

Perhaps it helps. Good luck

 

 

0 Kudos
Highlighted
Participant
Participant
243 Views
Registered: ‎01-27-2017

Hi Hans,

Thanks for the feedback but unfortunatly I need this 2-GB memory space on DMA Bypass and 64-bit enable on KC705.

I don't have any problem on Virtex7 Ultrascale though with 128-GB memory space.... which is quiete odd.

The only solution I have found so far is to use the "AXI Memory Mapped to PCie" Endpoint interconnected with CDMA for KC705.

 

0 Kudos
Highlighted
Newbie
Newbie
236 Views
Registered: ‎08-13-2020

Hi Xavier,

I mean "try with 1MB" to check if the problem is still there, only for a test.

The final configuration is another theme.

Best regards, Hans

 

 

0 Kudos
Highlighted
Participant
Participant
198 Views
Registered: ‎01-27-2017

Hi Hans,

I have already tried with 1MB memory space but I got the same behavior.

Regards,

Xavier

0 Kudos