[FS#687] Meraki MR24: Ethernet interface not detected correctly if cable not plugged at boot time

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Russell Senior (russell) 

Attached to Project - LEDE Project
Summary - Meraki MR24: Ethernet interface not detected correctly if cable not plugged at boot time
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Medium
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details -  - Device problem occurs on

Meraki MR24 (apm821xx)

 - Software versions of LEDE release, packages, etc.

Tested reboot-3921-g3169a6a7ad, but it's been a problem since at least last September.

 - Steps to reproduce
   
Disconnect ethernet cable, apply power, wait until device has booted, plug in ethernet, check for interfaces, no eth0 is listed.

This appears to be a problem during probing of the AR8035 Phy chip. When ethernet has no link, the phy detection fails, and eth0 is not created.  Plugging ethernet later has no effect, because there is no interface as far as the kernel is concerned.  The relevant part of the boot log looks like this:

this is the failing case:


[    0.876611] /plb/opb/emac-rgmii at ef601500: input 0 in RGMII mode
[    0.882532] /plb/opb/ethernet at ef600c00: reset timeout
[    0.888546] /plb/opb/ethernet at ef600c00: can't find PHY!


and the succeeding case:


[    0.876672] /plb/opb/emac-rgmii at ef601500: input 0 in RGMII mode
[    0.883952] eth0: EMAC-0 /plb/opb/ethernet at ef600c00, MAC 00:01:73:01:23:41
[    0.890822] eth0: found Atheros 8035 Gigabit Ethernet PHY (0x01)




 

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=687