[PATCH] net: macb: add TX stall timeout callback to recover from lost TSTART write

[Théo Lebrun]

On Fri Jun 12, 2026 at 3:03 PM CEST, Andrea della Porta wrote:
> On 14:53 Fri 12 Jun     , Nicolai Buchwitz wrote:
>> On 12.6.2026 14:51, Andrea della Porta wrote:
>> > > The commit message describes it as RP1 specific, but it gets applied
>> > > to all
>> > > other variants?
>> > 
>> > I've seen this issue happening only on RaspberryPi 5, but AFAIK it
>> > could affect also other MACB blocks connected through PCIe, so it
>> > may be widespread (even though it should have probably already been
>> > noticed in the past). In the orginal driver there's no timeout callback
>> > defined and this is much like pretgending the issue causing the timeout
>> > to happen to go away without doing anything (whatever the cause ot the
>> > specific hw are). So in my opinion we can just extend that to all MACB.
>> > Or maybe we should execute the restart conditionally on
>> > .compatible = "raspberrypi,rp1-gem"?
>> 
>> I just observed the issue once, but other people reported it to be happen
>> more
>> frequently. If we can narrow down a reproducer, it would be good to test on
>> other
>> blocks too (like EyeQ at Théo's).|
>> 
>> So maybe you can imagine a good repro for this issue?
>
> Sure, it's happening quite often during bulk dataflow, at least
> on my RPi5.
> It can be reproduced with the following, issued from the DUT:
>
>   iperf -c <SERVER_IP> -P 10 -t 3000 -w 4M -i 1
>
> plus, of course, the related command on server side: iperf -s.
>
> It usually happens a couple of times withing a few hours.

Thanks for the reproducer command; I'll run it next week.
I'd be surprised if it reproduced on hardware that isn't the Pi 5.

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com