Toradex SMARC iMX95 with 5G RTL8251B ethernet integration issue

Govind1807 · August 27, 2026, 2:18pm

Hi,

I’m working on the RTL8251B integration with the imx95 toradx som. We are using the latest version of som v1.2A only. In that, we have sucessfully integrated the RTL8251B 5G ethernet with phy-mode 5g-base-r but in this the MAC allocation was random allocating and if we set the static ip also not working, ping is unreachable. We tried the all the ways from our side but we haven’t sort out this issue. If we use any other mode also we are getting the same issue. If we use usxgmii phy mode means, the mdio is not working even the end2 node also not created. I will attach all the logs for your reference. Could you please assist on this issue?

ToradexAI · August 27, 2026, 2:18pm

Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

I can see you’re working with the SMARC iMX95 V1.2A module and experiencing issues integrating the RTL8251B 5G Ethernet PHY. However, I need to clarify a few important points about your setup.

Hardware Clarification Needed

First, could you confirm which exact version of Torizon OS or BSP you are running? You can use the tdx-info command to get detailed information about your system.(1)

Known Hardware Considerations for V1.2A

The SMARC iMX95 V1.2A that you mentioned is documented to have specific changes compared to earlier versions. According to the revision history, V1.2A includes fixes for boundary scan and JTAG debugging issues, and the eMMC part number was changed from Skyhigh S40FC032C3B1I00000 to Micron MTFC32GBCAQTC-IT.(1)

Ethernet Interface Information

The SMARC iMX95 module features up to 2 Gigabit Ethernet PHYs with IEEE1588 support directly on the module, and a third Ethernet MAC with a SGMII/USXGMII interface available for incorporating a 2.5 or 10-Gigabit Ethernet PHY on the carrier board.(2)

Regarding Your Integration Issue

The specific RTL8251B PHY integration you’re attempting involves carrier board-level implementation using the SGMII/USXGMII interface. From your description:

Random MAC allocation - This suggests the network interface is being created but lacks proper configuration
MDIO not working with USXGMII - This indicates potential device tree configuration issues
Static IP not working - This could be related to PHY link establishment

Unfortunately, the available documentation does not contain specific device tree examples or configuration guidance for integrating external 5G/10G Ethernet PHYs like the RTL8251B with the SMARC iMX95’s SGMII/USXGMII interface.

Recommended Next Steps

To properly assist you, I would need:

Your exact OS version (Torizon OS or BSP version)
Your device tree configuration for the RTL8251B
Complete dmesg logs showing the PHY initialization
Your carrier board design details

For complex carrier board integrations involving high-speed Ethernet PHYs, I recommend:

Visit Community to share your device tree configuration and detailed logs where the engineering team can provide specific guidance.

Visit GitHub to review reference device tree implementations for similar PHY integrations.

Would you like a general answer based on common Ethernet PHY integration practices, or would you prefer to gather the additional information first?

Best regards,
Toradex AI Assistant.

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Govind1807 · September 4, 2026, 10:37am

Hii,

Gentle Reminder to response this issue..!

ToradexAI · September 4, 2026, 10:38am

Thank you for the follow-up. I understand you need assistance with the RTL8251B 5G Ethernet integration on your SMARC iMX95 module.

Critical Information Still Needed

Before I can provide specific guidance, I need you to confirm:

Which OS and exact version are you running? (e.g., Torizon OS 7.2.0, BSP 6.x, etc.)
Can you share your device tree configuration for the RTL8251B PHY node?
Which Ethernet MAC are you using? (The SMARC iMX95 has multiple Ethernet interfaces)

You can get system information by running:

tdx-info

Learn more about tdx-info

Understanding SMARC iMX95 Ethernet Capabilities

The SMARC iMX95 provides:(1)

2x Gigabit Ethernet PHYs with IEEE1588 support directly on the module
1x additional Ethernet MAC with SGMII/USXGMII interface for 2.5G or 10G PHY on carrier board

For your RTL8251B 5G Ethernet integration on the carrier board, you would be using the SGMII/USXGMII interface.(1)

Common Issues with External PHY Integration

Based on similar Ethernet PHY integration cases, your symptoms suggest:

1. Random MAC Address

This typically indicates the device tree is missing the local-mac-address property or U-Boot is not setting it properly.

2. MDIO Not Working with USXGMII

When you switch to USXGMII mode and MDIO stops working, this often means:

Incorrect phy-mode property
Missing or incorrect MDIO bus configuration
Clock configuration issues
Pinmux problems

3. Static IP Not Working / Ping Unreachable

This usually indicates:

PHY link is not established properly
phy-handle reference is incorrect
Missing or incorrect PHY reset GPIO configuration

Device Tree Structure Guidance

Based on Toradex device tree conventions,(2)(3) your device tree should follow this structure:

SoC Level - Defines the Ethernet MAC controller
Module Level - May include module-specific configurations
Carrier Board Level - Your RTL8251B PHY configuration goes here

For the Ethernet MAC node, you need to ensure:(3)

Correct phy-mode (either "5gbase-r" or "usxgmii")
Proper phy-handle reference to your PHY node
MDIO bus configuration with correct address
PHY reset GPIO if applicable
Appropriate clock configuration

What I Need From You

To provide specific device tree guidance, please share:

Your current device tree overlay or modification for the RTL8251B
Complete dmesg | grep -i eth output
Output of ip link show
Your tdx-info output

Support Resources

For complex carrier board integrations like high-speed Ethernet PHYs:

Visit Community - Share your complete device tree configuration and logs for detailed engineering support.

Visit GitHub - Review reference implementations in the meta-toradex-torizon repository.

Without seeing your actual device tree configuration and knowing your exact OS version, I cannot provide more specific guidance. The available documentation does not include RTL8251B-specific examples for the SMARC iMX95.