I find a bug.
step1 : e1000e 82574L connected to embedded device whose nic speed 100M by poe power.
step2: e1000e connected to embedded device whose nic speed 1000M by poe power.
and then, it link with 1000M device by power, can't Tx and Rx.
it try to send a frame, it's led will be blink like a frame pass it.
link partner send a frame to it, led will be blink as like a frame by received. but MAC not
set link portner's speed as 100M, communitation is ok.