Ethernet reinit on phyCORE hangs the device

Sascha Hauer sha at
Tue Jun 14 01:27:11 PDT 2022

On Tue, Jun 14, 2022 at 09:12:23AM +0200, Andrej Picej wrote:
> Hi all,
> when testing barebox ethernet on i.MX6 (phyCORE) we encountered a bug:
> the ethernet re-init on barebox doesn't work! If we do:
> $ ifup eth0
> $ ifdown eth0
> and then:
> $ ifup eth0
> $ ping HOST_IP
> the device hangs and can only be saved by resetting the board manually.

I can confirm the behaviour is the same here.

> We narrowed the problem down to the "fec_tx_task_enable". It seems that
> enabling tx task with writing to TDAR reg hangs the device shortly after.
> Did you guys maybe encounter something similar on i.MX6 boards or on any
> other boards?
> I guess this is a really specific problem as people don't normally do
> ifup/ifdown with ethernet in bootloader :D.

Nope :)

> Do you have any idea what could be the reason or how could this be solved?
> Any useful information would be greatly appreciated.

Part of the problem is that fec_halt() tears down the device completely.
The counterpart of that is fec_init(), but that is called from during
probe only. I think fec_init() should be called from fec_open() as well.

A quick test revealed this is really only part of the problem. The next
one is that fec_update_linkspeed() is not called on second open, so the
fec speed registers will not get their correct value.


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