imx6ul: fec: stuck on ifup after ifdown

[Lucas Stach]

On Mo, 2020-10-05 at 17:17 +0200, Sascha Hauer wrote:
> Hi Stefano,
> 
> On Mon, Oct 05, 2020 at 02:43:15PM +0200, Manni Stefano wrote:
> > Hi,
> > 
> > on a custom board based on a i.MX6UL using barebox v2020.08.1 'ifup eth0'
> > invoked after 'ifdown eth0' stucks forever.
> > 
> > Have you ever experienced something similar?
> 
> I can confirm the same happens here on an i.MX6q board on current
> master. I don't know what's happening here. The last thing I see is that
> fec_tx_task_enable() is entered. Strange enough the same works on i.MX53
> whereas on i.MX8M I get "ERROR: eth0: transmission timeout" on the
> second ifup.
> 
> This is really strange. It seems fec_tx_task_enable() brings down the
> whole SoC, but on the other hand the FEC works properly in a chainloaded
> barebox, which should - from the view of the ethernet controller - be
> the same as a repeated ifup/ifdown sequence.

There is a crucial difference between the two things: in a chainloaded
Barebox we go through the FEC driver probe again, before doing the next
ifup. When going through probe a full reset of the FEC peripheral is
done.

Regards,
Lucas