[U-Boot] [PATCH 1/1] dwc2 USB controller hangs with lan78xx

[Peter Robinson]

>>> This bug is the combination of dwc2 USB controller and lan78xx
>>> USB ethernet controller, which is the combination in use on
>>> the Raspberry Pi Model 3 B+.
>>>
>>> When the host attempts to receive a packet, but a packet has not
>>> arrived, the lan78xx controller responds by setting BIR
>>> (Bulk-In Empty Response) to NAK. Unfortunately, this hangs
>>> the USB controller and requires the USB controller to
>>> be reset.
>>>
>>> The fix proposed is to have the lan78xx controller respond
>>> by setting BIR to ZLP.
>>>
>>> Signed-off-by: Andrew Thomas <andrew.thomas at oracle.com>
>>
>> Tested-by: Peter Robinson <pbrobinson at gmail.com>
>>
>> Tested on the RPi 3B+ and certainly improves this situation a number
>> of Fedora users have seen.
>
>
>
> What exactly have you tested?
>
> Even with this patch, I am not reliably to reliably boot into grub. It
> almost seems as if the packet buffer keeps getting overwritten by newer
> packets so that by the time we process the old ones, the ones we wanted to
> see are gone.

Booting to grub and then a local system, it's seemed improved in terms
of stability for me and a few other users, at least was more
consistent in getting to grub without "Rx: failed to receive: -5" but
then from the various testing different Fedora users have seen prior
to this patch it seems that the issue is very
network/cable/environment specific. I'm fairly certain that this patch
doesn't fix the problem but it at least appears from current reports
to improve the situation for some users.

Peter