netdev - Re: net: dsa: realtek: silent indirect reg read failures on SMP

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Message-ID: <87h797gmv9.fsf@bang-olufsen.dk>
Date:   Thu, 10 Feb 2022 08:13:46 +0000
From:   Alvin Šipraga <ALSI@...g-olufsen.dk>
To:     Luiz Angelo Daros de Luca <luizluca@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Arınç ÜNAL <arinc.unal@...nc9.com>
Subject: Re: net: dsa: realtek: silent indirect reg read failures on SMP

Hi Luiz,

Thanks for the info.

Luiz Angelo Daros de Luca <luizluca@...il.com> writes:

>> > So I used this command:
>> >
>> >     while true; do phytool read swp2/2/0x01; sleep 0.1; done
>>
>> I'll test it and report.
>
> In my single processor device, I got stable readings:
>
> root@...nWrt:/# while true; do phytool read lan1/2/0x01; done | time awk '!a[$1]
> ++'
> 0x79c9
> ^CCommand terminated by signal 2
> real    4m 56.44s
> user    0m 1.61s
> sys     0m 0.72s
>
> And most of the time I was executing three copies of that loop in parallel.
> I tried with and without my patches. All of them resulted in the same behavior.
>
> Sorry but I believe my non-SMP device is not "affected enough" to help
> debug this issue. Is your device SMP?

Yes, it's SMP and also with PREEMPT_RT ;-)

But no problem, I will look into this and get back to you in this thread
if I need any more feedback. Thanks for your help.

Kind regards,
Alvin

>
> ---
> Luiz