netdev - Re: [PATCH net-next] net: dsa: realtek: rtl8365mb: read phy regs from memory when MDIO

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Message-ID: <Yga6ukIalICeD8KK@lunn.ch>
Date:   Fri, 11 Feb 2022 20:36:26 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Alvin Šipraga <ALSI@...g-olufsen.dk>
Cc:     Luiz Angelo Daros de Luca <luizluca@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "vivien.didelot@...il.com" <vivien.didelot@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "olteanv@...il.com" <olteanv@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "arinc.unal@...nc9.com" <arinc.unal@...nc9.com>
Subject: Re: [PATCH net-next] net: dsa: realtek: rtl8365mb: read phy regs
 from memory when MDIO

> I am not sure I agree with your description here. It is more likely that
> there is just a bug in the driver, rather than some problem with
> indirect PHY register access "when the switch is under stress". Please
> see my reply to your earlier thread.

I tend to agree. Reading PHY registers happens quite often due to
polling every second, so if there is a problem, this is where you see
it. But how do you know the same issue does not appear somewhere else
in the driver?

Maybe add code to dump the ATU, poll it frequently, and see if any
entries change unexpectedly?

	Andrew