[En-Nut-Discussion] Emac Reset

Timothy M. De Baillie debaillie at ciholas.com
Wed Apr 1 16:39:00 CEST 2009

I'm having a problem with the SAM7X256 ethernet locking up with a 
particular PHY.  In fact it happens with more than one PHY, so I'm 
thinking this might be a nasty once in a blue moon OS bug.  I can detect 
this state rather easily (the PHY responds to any register request with 

I was wondering if there is a "good" way to restart the ethernet state 
machine without reseting the processor.  Now I have tried just ignoring 
the reset line and restarting the PHY.  This appears to make the PHY 
operate properly (answering back), but the OS is stuck in a stale state 
at this point (no ping, no telnet connections allowed...). 

Obviously if I could figure out why it was locking up in the first place 
(I don't know if it's an OS problem that causes the PHY to lock up, or 
vice versa) I could just fix the problem.  However since I don't have a 
repeatable enough test, I am having trouble narrowing this down.  So for 
now I would be "OK" with detecting the problem and "resolving" it.

So if anyone can help me get the ethernet state machine reset, I would 
highly appreciate it!

Thanks in advance,


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