Lane reversal on UPHY2 PCIe x4 for AGX Orin

Autonomous Machines Jetson & Embedded Systems Jetson AGX Orin
1

Hi,

We would like to use Jetton’s UPHY2(C7) as Configuration #2 with UPHY_RX6/TX6 to UPHY_RX9/TX9 as RootPoint in a 4-lane configuration. Is it possible to connect only these 4 lanes to EndPoint with lane reversal?
If it is possible, will Pinmux or driver modifications be required?

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Best Regards,
UNA

3

Hi,

Please connect lane 0~3 with correct order.

4

Hi Wayne,

Thank you for your reply.

Please allow me to clarify your response.

Q1: When using UHPY2 with PCIe x4, does this mean we need to use UPHY_RX2/TX2 (Lane 0), UPHY_RX3/TX3 (Lane 1), UPHY_RX4/TX4 (Lane 2) and UPHY_RX5/TX5 (Lane 3)?

Q2: If I do Lane Reversal, will I need to change software, including Pinmux?

Best Regards,
UNA

5

Q1: When using UHPY2 with PCIe x4, does this mean we need to use UPHY_RX2/TX2 (Lane 0), UPHY_RX3/TX3 (Lane 1), UPHY_RX4/TX4 (Lane 2) and UPHY_RX5/TX5 (Lane 3)?

Yes.

Q2: If I do Lane Reversal, will I need to change software, including Pinmux?

No, not needed. But I don’t suggest to do lane reversal. Better using common design.

6

Why can’t you recommend lane reversal?

Are there any restrictions? or do you mean that it is not recommended simply because there is no track record of lane reversal for PCIe?

Best Regards,
UNA

7

Hi,

We didn’t validate lane reversal in every software release.

It could be bug or something else. So basically I always suggest to directly follow the design as devkit or product design guide.

8

Hi,

OK, I understand that.

Best Regards,
UNA

10

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