Apalis i.MX8 - "No Ethernet Found" during DHCP/TFTP boot

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Troubleshooting Ethernet PHY Detection on Apalis iMX8 with Ixora

Your issue with “Unable to connect to PHY” and “No ethernet found” on the Apalis iMX8 with Ixora carrier board is likely related to several potential causes. Let me provide guidance based on the available documentation.

TFTP/NFS Boot Configuration

First, let’s verify your TFTP/NFS setup follows the documented procedure(1). Your DHCP configuration looks correct, but ensure you have the proper boot files in place:

sudo cp -Ppr /path to bootfs/* /srv/tftp/

(1)

The boot sequence should follow these steps(1):

  1. U-Boot obtains IP address and boot script name from DHCP server
  2. U-Boot executes the script, obtaining kernel image and device trees
  3. U-Boot sets kernel command line for NFS root filesystem mounting
  4. Linux uses DHCP again to get IP and root-path arguments

Known Ixora Carrier Board Issues

There’s a documented errata for the Ixora carrier board that could be relevant to your situation(2). The Ixora board features the Nexperia IP4791CZ12 HDMI ESD protection and level shifter, and there are known compatibility issues with certain modules(2).

Power Management and Regulators

Based on community discussions, the “deferred probe pending” error often indicates the driver is waiting for a resource like a regulator to become available(3). For custom implementations, you may need to configure an “always-on” regulator in your device tree(3):

The issue could be that the GPIO expander used to enable the power supply was not initialized(3). If your setup doesn’t have the same PCAL6416AHF GPIO expander as the standard Verdin Development Board, this initialization could be failing(3).

Debugging Steps

  1. Check U-Boot Network Variables: Verify your default network settings match the documented defaults(1):

    • ipaddr=192.168.10.2 (module IP)
    • serverip=192.168.10.1 (host IP)

  2. Verify TFTP Server Configuration: Ensure your TFTP server is serving /srv/tftp and contains the necessary boot files(1).

  3. Check Device Tree Configuration: The PHY detection issue might require device tree modifications specific to your hardware setup.

  4. Power Rail Investigation: Verify that the Ethernet PHY power rails are properly enabled and stable.

Service Restart Commands

After making configuration changes, restart the relevant services(1):

On Ubuntu:

sudo service isc-dhcp-server restart; service tftpd-hpa restart; service nfs-kernel-server restart

(1)

On Fedora:

systemctl restart dhcpd.service; systemctl restart nfs-server.service

(1)

Next Steps

Given the complexity of your setup and the specific hardware combination, I recommend:

  1. Checking if your Ixora board revision has any known errata that might affect Ethernet functionality
  2. Verifying the power management configuration for the Ethernet PHY
  3. Ensuring the correct device tree is loaded for your specific hardware combination
  4. Testing with a minimal configuration first before adding TFTP/NFS boot complexity

The fact that both U-Boot and Linux fail to detect the Ethernet suggests a hardware-level issue rather than just a software configuration problem.

Best regards, Toradex AI Assistant.

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