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

[LEDE Bugs]

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FS#687 - Meraki MR24: Ethernet interface not detected correctly if cable not plugged at boot time
User who did this - Russell Senior (russell)

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> Since I think this is something specific to the MR24 and since you said "but it’s been a problem since at least last September.". I think it must have been a issue from the beginning. Is this correct? Or do you remember an older version, were this was working as intended? 

I am unaware if it ever worked.  I think my initial foray into MR24 things dates from the same September period.

I tried the bind/unbind.  With ethernet unplugged at boot time, then plugged in, and running the suggested command, I get this:


echo 4ef600c00.ethernet > /sys/bus/platform/drivers/emac/bind
[   49.562867] /plb/opb/emac-rgmii at ef601500: input 0 in RGMII mode
[   49.568842] /plb/opb/ethernet at ef600c00: reset timeout
[   49.573925] /plb/opb/ethernet at ef600c00: can't find PHY!
ash: write error: No such device


With ethernet plugged at boot time, I see this:


# ls -al /sys/bus/platform/drivers/emac
drwxr-xr-x    2 root     root             0 Apr  8 18:33 .
drwxr-xr-x   23 root     root             0 Apr  8 18:33 ..
lrwxrwxrwx    1 root     root             0 Apr  8 18:33 4ef600c00.ethernet -> ../../../../devices/platform/plb/plb:opb/4ef600c00.ethernet
--w-------    1 root     root          4096 Apr  8 18:33 bind
--w-------    1 root     root          4096 Apr  8 18:33 uevent
--w-------    1 root     root          4096 Apr  8 18:33 unbind


With the MR24 booted with no ethernet, the GPIOs dump as follows:


# cat /sys/kernel/debug/gpio
gpiochip2: GPIOs 448-463, parent: pci/0000:44:00.0, ath9k-phy1:
 gpio-458 (                    |ath9k-phy1          ) out lo

gpiochip1: GPIOs 464-479, parent: pci/0000:43:00.0, ath9k-phy0:
 gpio-474 (                    |ath9k-phy0          ) out lo

gpiochip0: GPIOs 480-511, /plb/opb/gpio at ef600b00:
 gpio-496 (                    |Reset button        ) in  hi
 gpio-497 (                    |?                   ) out hi
 gpio-498 (                    |?                   ) out lo
 gpio-499 (                    |?                   ) out hi
 gpio-500 (                    |?                   ) out lo
 gpio-501 (                    |?                   ) out hi
 gpio-502 (                    |?                   ) out hi
 gpio-503 (                    |?                   ) out hi



With ethernet plugged at boot time, I get these GPIOs:


# cat /sys/kernel/debug/gpio 
gpiochip2: GPIOs 448-463, parent: pci/0000:44:00.0, ath9k-phy1:
 gpio-458 (                    |ath9k-phy1          ) out lo    

gpiochip1: GPIOs 464-479, parent: pci/0000:43:00.0, ath9k-phy0:
 gpio-474 (                    |ath9k-phy0          ) out lo    

gpiochip0: GPIOs 480-511, /plb/opb/gpio at ef600b00:
 gpio-496 (                    |Reset button        ) in  hi    
 gpio-497 (                    |?                   ) out lo    
 gpio-498 (                    |?                   ) out lo    
 gpio-499 (                    |?                   ) out hi    
 gpio-500 (                    |?                   ) out lo    
 gpio-501 (                    |?                   ) out hi    
 gpio-502 (                    |?                   ) out hi    
 gpio-503 (                    |?                   ) out hi    


I see gpio-497 has s different state, which is interesting.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=687#comment2349