Using M.2 Key-M (2280) slot on Jetson Orin Nano as PCIe x4 root port for external PCIe device via riser

Robotics & Edge Computing Jetson Systems Jetson Orin Nano
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Hi,

I have a hardware question about the Jetson Orin Nano Super Developer Kit PCIe usage.

I’m hoping to use the M.2 Key-M 2280 slot with an M.2-to-PCIe x4 riser cable to connect a standard external PCIe Gen2 x4 video capture/keyer card (instead of a NVMe SSD).

Before I commit to buying the developer kit, I’d like to confirm a few details first:

  1. Does the 2280 Key-M slot expose a normal PCIe root port (PCIe 3.0 x4), or is it restricted to storage/NVMe use only?

  2. Are non-storage PCIe devices (like video capture cards) expected to enumerate and work through this slot?

  3. Are there any lane-sharing, firmware, or device-tree limitations that would prevent using this slot with generic PCIe devices?

I understand the Nano runs PCIe at Gen3 (instead of Gen4), which is fine for the video capture card I’m looking to connect. I just want to make sure there are no functional restrictions on using this slot for this.

Thank you very much!

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*** Please note that this reply is generated by LLM automatically ***

Based on the provided context, I’ll address your questions about the Jetson Orin Nano Super Developer Kit’s PCIe usage.

  1. Does the 2280 KeyM slot expose a normal PCIe root port (PCIe 3.0 x4) or is it restricted to storage/NVMe use only?

The Jetson Orin Nano series has a PCIe controller that supports up to Gen3 speed. The M2 KeyM 2280 slot is connected to the PCIe C4 controller, which supports dual mode (root port or endpoint) and has a maximum lane width of x4. This suggests that the slot is not restricted to storage/NVMe use only and can be used as a normal PCIe root port.

  1. Are non-storage PCIe devices like video capture cards expected to enumerate and work through this slot?

The documentation does not explicitly state that non-storage PCIe devices are not supported. However, it does mention that the PCIe C4 controller supports dual mode, which implies that it can be used for both storage and non-storage devices. Additionally, the fact that the slot is connected to a root port controller suggests that it should be able to enumerate and work with non-storage PCIe devices.

  1. Are there any lane-sharing firmware or devicetree limitations that would prevent using this slot with generic PCIe devices?

The documentation mentions that USB 3.2, MGBE, and PCIe share UPHY Lanes, and that the Product Design Guide provides information on supported UPHY configurations. However, it does not explicitly state that there are any lane-sharing limitations that would prevent using the slot with generic PCIe devices. It is possible that there may be some limitations or restrictions, but they are not clearly documented.

  1. Comparison with other Jetson modules

For comparison, the Jetson Orin NX series also has a PCIe controller that supports up to Gen4 speed, but it is not clear if the M2 KeyM 2280 slot on the Jetson Orin NX module is restricted to storage/NVMe use only. The Jetson AGX Orin module has a different PCIe controller configuration, with two PCIe slots that support x4 and x2 lanes, respectively.

In summary, based on the provided context, it appears that the Jetson Orin Nano Super Developer Kit’s M2 KeyM 2280 slot can be used as a normal PCIe root port and may support non-storage PCIe devices like video capture cards. However, there may be some limitations or restrictions that are not clearly documented, and it is recommended to consult the Product Design Guide and other relevant documentation for more information.

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Does the 2280 Key-M slot expose a normal PCIe root port (PCIe 3.0 x4), or is it restricted to storage/NVMe use only

Yes, it is working as a normal PCIe RP but generally we expect you use the NVMe storage for it.

Are non-storage PCIe devices (like video capture cards) expected to enumerate and work through this slot?

didn’t test this before. But ideally lspci shall show the card.

Are there any lane-sharing, firmware, or device-tree limitations that would prevent using this slot with generic PCIe devices?

No, there is not.

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Great! Thank you both, that’s super helpful