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

[Théo Lebrun]

On Fri Jun 12, 2026 at 4:28 PM CEST, Théo Lebrun wrote:
> 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.

Sorry for the two-step message. I forgot to mention I'd prefer to have
the timeout callback on all platforms: don't reserve it for Pi 5.

Thanks,

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