Does the CD8180 have one or many PCI controllers (for the 1x PCIe + 2x M.2 slots)

Orion Series O6
1

Hi,

Internally how are the three PCIe slots wired?

In total there are five PCIe slots - the x8 PCI slots, the 2x M.2 slots, and then thre two Realtek ethernet controllers are connected via PCIe separately also.

This page https://sbcwiki.com/docs/soc-manufactures/cix/cd8180-p1/ shows under Block Diagram that the PCI slots are wired separately.

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These slides from Radxa https://dl.radxa.com/orion/o6/radxa_orion_o6_announcement_presentation_2024_12_18.pdf show the following. Here it looks like maybe there’s two PCI controllers internally with 8 lanes each, and ONE of them supports bifurcation? But perhaps on the bifurcation controller data will still never go between devices.

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From dmesg, lspci and various documents, what do you see?

Does the CD8180 have in total five separate PCI controllers?

In contrast with for example having a PCI switch internally, that could let data pass directly between those five PCI slots. In csae of separate controllers, data would never pass automatically.

Thanks

@jack

2

I can see a 4 pci bridges, one for each NIC, the 4.0 slot, and m2 slot. I’m not using the e-key but i will see if i can test it.

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3

I can also see one bridge/root per connected device:

$ sudo lspci -nn
0000:90:00.0 PCI bridge [0604]: CIX Technology Group Co., Ltd. CIX P1 CD8180 PCI Express Root Port [1f6c:0001]
0000:91:00.0 Non-Volatile memory controller [0108]: Kingston Technology Company, Inc. NV3 NVMe SSD [TC2201] (DRAM-less) [2646:5025]
0001:00:00.0 PCI bridge [0604]: CIX Technology Group Co., Ltd. CIX P1 CD8180 PCI Express Root Port [1f6c:0001]
0001:01:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8126 5GbE Controller [10ec:8126] (rev 01)
0002:30:00.0 PCI bridge [0604]: CIX Technology Group Co., Ltd. CIX P1 CD8180 PCI Express Root Port [1f6c:0001]
0002:31:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8126 5GbE Controller [10ec:8126] (rev 01)
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4

The e-key is a PCI socket too so it should have a root port too, so there should be five root ports in total right?

  • 1x for the x16 socket slot (8 lanes),
  • 1x for the 22x80mm M-key slot (4 lanes),
  • 1x for the 22x30mm E-key slot (2 lanes), and
  • 2x one each for the two 5gbe NIC:s (each 1 lane)?

What is the PCI bridge [0604]: CIX Technology Group Co., Ltd. CIX P1 CD8180 PCI Express Root Port [1f6c:0001] silicon actually - is it a proper root or is it a bridge?

Is there a PCI bus whereby through which the roots can communicate with each other outside of the OS/CPU drivers’ active facilitation?

(PCI devices connected to one and the same PCI switch chip can apparently communicate directly with each other.)

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