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Registered: ‎02-08-2018

DMA/Bridge Subsystem for PCI Express in AXI Bridge IP: No configuration space access

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Hi,

 

we use the "DMA/Bridge Subsystem for PCI Express in AXI Bridge IP" in root port mode in a ZU19EG-FFVC1760 device.

If we try to read the configuration space (Addr. 0x0 - 0x12F) of the bridge during enumeration the AXI-Lite read cycle is not finished -> The PS application gets an exception. When we read registers after the config space (Addr. 0x130, 0x134, ...)  it works fine.

 

IP-Config:

  • Vivado 2018.2
  • Root port mode
  • x2 Gen2
  • Refclk = 250 MHz
  • PCIe-block X1Y0
  • GT: Quad 225

As stated in PG194 (table 2-4) the accessibility of the config space is "Read only in an endpoint" (RO - EP). What does it mean? Can i read this registers only in endpoint configuration and not in root port mode?

Otherwise, when I use the ZCU106 with a similar setup (root port, x1 Gen2, Refclk = 125 MHz) a successful access to the config space is possible.

 

Are there any differences between these different FPGA devices? Which effect can cause such invalid config space accesses in root port mode?

 

 

Thank's a lot!

Christian

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878 Views
Registered: ‎02-08-2018

Thank's!

 

The problem was that after the "Run block automation" process in the block design Vivado disables the cfg_mgmt_if parameter of the bridge even when they is configured as root port. It is necessary to set this parameter manually back to "true".

 

Regards

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-02-2007

read only in EP means when configured as EP, this address can only be read but not writeable.

Not all the address in 00-12f are valid for a device.

Please pay attantion to the address 

C_BASEADDR and  AXI4-Lite Slave address bit 28

check if they are set correctly according to pg194

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Registered: ‎02-08-2018

Thank's!

 

The problem was that after the "Run block automation" process in the block design Vivado disables the cfg_mgmt_if parameter of the bridge even when they is configured as root port. It is necessary to set this parameter manually back to "true".

 

Regards

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