we have designed Carrrier board for the Jetson AGX orin from the reference of P3737 design files.
we have changed the PCIe Connector from the X16 to X8 , anyway we connecting x8 bus to the SOM right in the P3737 also.
I have tested that all required voltages for the 12V 3.3V and +3.3V aux also coming up to the PCIe slot. then why adaptor is not getting enumarated by the SOM.
FYI, i am not getting “PCIE_3V3_EN” so, i have removed that Ic U127 and shorted pin 5 to pin1. so that 3.3V aux also going to PCIe slot.
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Based on the provided context, I’ll address the question and provide a comprehensive answer.
The issue at hand is that the custom-designed carrier board for the Jetson AGX Orin, which is based on the P3737 reference design, is not enumerating the PCIe adapter. The design changes made include:
Changing the PCIe connector from X16 to X8.
Connecting the X8 bus to the SOM.
Verifying that the required voltages (12V, 3.3V, and 3.3V aux) are present at the PCIe slot.
Removing the U127 IC and shorting pin 5 to pin 1 to ensure the 3.3V aux voltage is present at the PCIe slot.
Despite these changes, the SOM is not enumerating the PCIe adapter.
To troubleshoot this issue, let’s compare the custom design with the original P3737 reference design:
PCIe connector: The original P3737 design uses an X16 PCIe connector, while the custom design uses an X8 connector. Although the X8 bus is connected to the SOM, it’s essential to verify that the device tree configuration is updated to reflect the change in PCIe lane configuration.
Device tree configuration: The device tree configuration might need to be updated to accommodate the change in PCIe lane configuration. The original P3737 design might have a device tree configuration that assumes an X16 PCIe connector. The custom design should update the device tree configuration to reflect the X8 PCIe connector.
PCIe voltage rails: The custom design has verified that the required voltage rails (12V, 3.3V, and 3.3V aux) are present at the PCIe slot. However, it’s crucial to ensure that these voltage rails are properly connected to the PCIe adapter and that the adapter is powered correctly.
U127 IC removal: The removal of the U127 IC and shorting pin 5 to pin 1 might have affected the PCIe adapter’s power-up sequence. It’s essential to verify that the PCIe adapter is powered correctly and that the power-up sequence is not affected by this change.
To resolve the issue, I recommend the following steps:
Update the device tree configuration: Update the device tree configuration to reflect the change in PCIe lane configuration from X16 to X8. This might involve modifying the device tree source files or updating the device tree binary.
Verify PCIe voltage rails: Double-check that the PCIe voltage rails (12V, 3.3V, and 3.3V aux) are properly connected to the PCIe adapter and that the adapter is powered correctly.
Verify PCIe adapter power-up sequence: Ensure that the PCIe adapter’s power-up sequence is not affected by the removal of the U127 IC and the shorting of pin 5 to pin 1.
Test with a different PCIe adapter: Try testing the custom carrier board with a different PCIe adapter to rule out any issues with the specific adapter being used.
By following these steps, you should be able to identify and resolve the issue preventing the SOM from enumerating the PCIe adapter.
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I’m now able to get the PCIe card detected. I did not change any configurations for this — it turned out to be a hardware issue. The PCIe connector was not soldered properly.
Thank you very much for all the support you provided throughout this troubleshooting process.
