[En-Nut-Discussion] PHY set up, cable plugging, re-plugging

[Dave Warren]

I just got my own SAM7X based board to work with a different PHY.(National 
DP83848i). It got me thinking about the link negotiation.At the moment 
Ethernut will stall in EmacReset() if the network cable is unplugged. 
However once configured you can unplug/plug the cable several times and the 
PHY automatically sets up with correct modes. In EmacReset the code finishes 
with configuring the EMAC for the PHY mode.

How about if we split the EmacReset() code so that it resets and programs 
the PHY then checks once to see if link is OK. If link OK it can program the 
EMAC mode and return, if link is bad it just returns anyway. Then in the 
idle thread we can check the PHY status, if it changes, say link is 
established we can program the EMAC mode.

I think this would avoid the stall if Ethernut starts up unplugged and may 
deal with the case of plugging a running Ethernut into a different hub 
perhaps with different abilities Speed or Full/Half duplex ect.

Best regards

Dave Warren