VAR-SOM-MX8 Could not get PHY for FEC0

[jens0501]

Hi,

We have a custom board which houses the var-som-mx8. This som gets booted via eMMC which we flashed via another board and a sd card via the 'install_debian.sh' script. At the moment we are not able to get the ethernet 0 interface working. The ethernet cable is plugged in and verified to be working, but we see no activity on the ACT or LINK led (these stay off) and in the u-boot menu (which I included as a text file in this ticket) we see following message:

"Net: eth0: ethernet@5b040000Get shared mii bus on ethernet@5b050000
Could not get PHY for FEC0: addr 5"

In Linux we see that the eth0 interface is DOWN, but we cannot bring this UP. The ethernet connections on our carrierboard are already verified by Variscite and in this ticket I also included a screenshot of the ethernet connector which is directly connected (albeit via long traces) to the som. At this moment I am maybe suspecting a configuration issue of some kind. I have also included the devicetree that we are using which is just a default tree that was already available. what could be the cause of the problem?

EDIT: When I try 'mdio info' in u-boot I get the message 'no mdio bus found' and when I try 'mii info' I get the message 'no such device <NULL>'

Best regards

[Sanket_Parekh]

Hi @jens0501 

I hope you are doing well.

Please make sure that PHY Address is correctly set.

One can refer to fsl-imx8qm-mek.dts (u-boot dts ) and imx8qm-mek.dts (linux dts) for device tree configuration.

Please make sure that your board file in the /board directory contains proper initialization and resource allocation (pad , power domain ..) as done in /board/freescale/imx8qm_mek/imx8qm_mek.c

"fec 5b050000.ethernet: ignoring dependency for device, assuming no driver"

above issue could arise due to device tree mismatch.

Please provide me with device tree source file for u-boot and linux kernel.

Please try using Latest BSP.

Thanks & Regards,

Sanket Parekh

[jens0501]

Hi @Sanket_Parekh,

Thanks for the response. Included in this post, you can find the devicetree files and the board file that I have used.

A quick note, we have only included hardware on our board for the ethernet0 interface (the one with PHY assembled on the SoM) so we are not using the ethernet1 interface. Can this cause problems for eth0 if eth1 is still defined in the devicetree, but when it cannot detect any hardware?

Best regards

[Sanket_Parekh]

Hi @jens0501 

I hope you are doing well.

If the ethernet1 interface is not used then one can add status = "disabled"; in the device tree node.

Please make sure that all required kernel configuration options are in defconfig.

Please make sure that the mac address is fused correctly or set in the kernel command line.

Thanks & Regards,

Sanket Parekh

[jens0501]

Hi, @Sanket_Parekh,

I have changed the status of the ethernet1 interface to disabled and I believe the MAC address is correctly set (if I do printenv in u-boot I see that ethaddr has a MAC address). I also believe that all kernel configurations are correctly set since I'm using a standard build which is meant to be used with the symphonyboard and our customboard uses the same pins as the symphonyboard for most interfaces. Is there a specific kernel setting I should check to be sure?

Best regards

[Sanket_Parekh]

Hi @jens0501 ,

I hope you are doing well.

The "no mdio bus found" error generally occurs if the mdio pads are not configured correctly or PHY is not correctly connected.

Please make sure that the u-boot device tree is configured as in /arch/arm/dts/fsl-imx8qm-var-som.dts

Please make sure that reset gpio and mdio pins are correctly connected in the customer board.

Please provide me with an ethernet mdio interface for further debugging.

Thanks & Regards,

Sanket Parekh

[jens0501]

Hi @Sanket_Parekh,

I have compared the u-boot device trees and the only difference I see is that in our device tree in the fec1 block, we have in this: phy-reset-post-delay = <100>; but in the tree you shared there is this: phy-reset-post-delay = <20>;

Could this have an effect? I was not able to test this yet.

I have included 2 screenshots of the ethernet interface between the ethernet port and the pins of the sodimm connector. On the sodimm screenshot Ethernet1.TX corresponds with MDI_A, Ethernet1.RX with MDI_B, ethernet1.RX_TX1 with MDI_C and ethernet1.RX_TX2 with MDI_D. There are no further components on the ethernet interface between the sodimm connector and the ethernet port. However, the ethernet traces are relatively long.

Best regards,

[Sanket_Parekh]

Hi @jens0501 

I hope you are doing well.

I couldn't find any NXP part in the attached schematics.

Is there any change in logs after disabling eth1? if yes then provide me with the latest logs.

One can refer to i.MX 8QuadMax Multisensory Enablement Kit (MEK) schematic.

MCIMX8QM-CPU MEK – Schematic

Please mention the part number of Ethernet PHY.

Thanks & Regards,

Sanket Parekh

[jens0501]

Hi @Sanket_Parekh,

We are using the VAR-SOM-MX8 module from Variscite (https://www.variscite.com/product/system-on-module-som/cortex-a72/var-som-mx8-nxp-freescale-i-mx8/) which uses the iMX8 QuadMax from NXP. This module is connected to the Sodimm connector you can see on the schematics. The ethernet PHY on this module should be the ADIN1300.

I have included the boot log with a devicetree (set with the 'setenv fdt_file' command) where eth1 is disabled. There is still no etehrnet in either Linux or u-boot.

Best regards,

[Sanket_Parekh]

Hi @jens0501 

I hope you are doing well.

From the logs, PHY seems to be correctly detected and initialized.

"fec 5b040000.ethernet: ignoring dependency for the device, assuming no driver",

above error occurs due to a change in kernel framework and might not affect ethernet.

Please provide me with the commands or tests you are using for ethernet.

Are there any logs in dmesg when plugging or unplugging the ethernet cable?

Please share the output of the below commands.

# ifconfig -a

# ifdown eth0
# ifup eth0

Thanks & Regards,

Sanket Parekh