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smegeed
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Registered: ‎04-01-2021

Root Complex PCIe Configuration Registers Offset 0x130 and greater

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Based on PG194, my root complex (DMA/Bridge Subsystem for PCI Express) can read back ctl0 registers.

Upto register 0x12F, everything matches the documentation.  Anything 0x130 and higher doesn't match the document.  I don't see Bridge Info, Bridge Status and Control etc.

Thank you

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seamusbleu
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Registered: ‎08-12-2008

Well, if you squint your eyes just right the documentation seems ok.  I wouldn't count of reserved values being equal to the reset value, and while I would have expected that if the gen3 supported bit was set, the gen2 bit would as well, you could think of them as being mutually exclusive.

seamusbleu_0-1631629184561.png

 

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smegeed
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Bump

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seamusbleu
Voyager
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Registered: ‎08-12-2008

I'm assuming you are using IP in AXI Bridge mode and are accessing these registers through the AXI-lite interface, correct?  My design, though endpoint, shows 0x130 is 0x0000_002C", which isn't exactly what I would think I'd see.  The rest of my registers are all 0's, except at 0x144 I have 0x0000_0885 which agrees with PHY Status/Control Register (currently running Gen2x4, link up).  What are you seeing for 0x130 - 14C?  

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smegeed
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Registered: ‎04-01-2021

Thank you for your time.

I'm in AXI Bridge mode reading the CTL registers through the AXI-Lite interface. 

This is what I see

0xa0000130: 0001000e 00000000 00000000 00000000 00000000 00003880
0xa0000148: 00000000 00000000 00000000 00000000 00000000 00000000

0x130 doesn't match at all. and 0x144 make sense sense I'm Gen3 x16

So looks like maybe only 0x130 doesn't match.  Maybe a bug in the documentation?

 

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seamusbleu
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Registered: ‎08-12-2008

Well, if you squint your eyes just right the documentation seems ok.  I wouldn't count of reserved values being equal to the reset value, and while I would have expected that if the gen3 supported bit was set, the gen2 bit would as well, you could think of them as being mutually exclusive.

seamusbleu_0-1631629184561.png

 

<== If this was helpful, please feel free to give Kudos, and accept as Solution if it answers your question ==>

View solution in original post