Ethernet issues on Colibri iMX6ULL

Technical Support
1

I have a Colibri iMX6ULL board in a Colibri Evaluation Board with Colibri-iMX6ULL_Reference-Minimal-Image-Tezi_5.7.6+build.29 installed.
I get no lights on the Ethernet port and ‘ip link’ reports eth0 as DOWN. Running ‘ip link set eth0 up’ seems to have no effect.
dmesg does not seem to report any error:
[ 19.897702] Generic PHY 20b4000.ethernet-1:02: attached PHY driver [Generic PHY] (mii_bus:phy_addr=20b4000.ethernet-1:02, irq=POLL)

I have also tried an Iris Carrier Board which exhibited the same symptoms. I have a Viola Board that I have yet to try (mostly because it doesn’t have good outputs for debug (video and/or UART).

This may be similar to this post which doesn’t have any stated resolution.

2

Hi, I’m the Toradex AI Assistant.

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Hello! Thank you for your detailed report.

Based on your description and logs, there are a few likely causes for the Ethernet issue on your Colibri iMX6ULL:

Key Checks

1. Hardware Connections

  • Make sure your Ethernet cable and the carrier board ports are working. Swap cables and ports to rule out a bad connection.
  • Check the COLIBRI_EVAL BOARD or IRIS BOARD LED indicators for LINK (LINK_AKT) and 100Mbit (SPEED100). Typically, at least the LINK LED should light up when a cable is connected to a live network (1).

2. Software and Device Tree

  • The message Generic PHY ... attached PHY driver with no errors suggests the driver is loaded, and the MDIO address is correct (for Colibri iMX6ULL, the default address is 0x02).
  • Double-check that no device tree overlays or custom configurations are disabling or incorrectly configuring the ethernet/phy. Are you using a custom device tree, or just the stock Reference-Minimal-Image?

3. Try Another BSP

  • There have been past reports about Ethernet links not coming up or the PHY not resetting properly on warm boot. Some of these were resolved in later software versions (2).
  • If possible, try updating to TorizonCore or a newer reference image, such as one based on BSP 6.x, to see if the problem persists.

4. Power Cycling

  • Cold boot (full power off/on), as opposed to software reboot, to fully reset the PHY.

5. Manual PHY Reset

  • If after a cold boot the LEDs still do not come on, the issue may be with the PHY reset signal or a device tree misconfiguration. On Torizon or Reference images, the device tree should already handle this, but it could be worth checking for any patches or overlays you may have added.

Additional Debug Commands

After connecting the cable and running ip link set eth0 up, please provide the output of:

  • dmesg | grep eth
  • ethtool eth0
  • mii-tool eth0 (if available)
  • lsmod | grep fec

These will help verify MAC/PHY status and loaded drivers.

Relevant documentation for further reading:

Let me know your findings after these checks, and I can suggest the next steps.

Best regards, Toradex AI Assistant.

3

I’ve tested the Colibri-iMX6ULL_Reference-Minimal-Image-Tezi_5.7.6+build.29 image on a Colibri iMX6ULL 512MB Wi-Fi / BT IT V1.1A module, and Ethernet is working as expected. This supports my initial suggestion that your Colibri iMX6ULL module may have a hardware issue.

Do you have another Colibri iMX6ULL module available for testing?

4

i do not. i just have this one as an evaluation module.

5

You can submit an RMA request . if module is defective it will be replaced.