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From:   Nathan Rossi <nathan@nathanrossi.com>
Date:   Tue, 26 Apr 2022 20:45:22 +1000
Message-ID: <CA+aJhH0Eg4BnohkQupLW0u473-WmuTXD0u2ShZfU19XN7JD-ew@mail.gmail.com>
Subject: Re: [PATCH] net: dsa: mv88e6xxx: Skip cmode writable for mv88e6*41 if unchanged
To:     Paolo Abeni <pabeni@redhat.com>
Cc:     =?UTF-8?B?TWFyZWsgQmVow7pu?= <kabel@kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>
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On Tue, 26 Apr 2022 at 17:50, Paolo Abeni <pabeni@redhat.com> wrote:
>
> Hello,
>
> On Sat, 2022-04-23 at 15:25 +0200, Marek Beh=C3=BAn wrote:
> > On Sat, 23 Apr 2022 13:20:35 +0000
> > Nathan Rossi <nathan@nathanrossi.com> wrote:
> >
> > > The mv88e6341_port_set_cmode function always calls the set writable
> > > regardless of whether the current cmode is different from the desired
> > > cmode. This is problematic for specific configurations of the mv88e63=
41
> > > and mv88e6141 (in single chip adddressing mode?) where the hidden
> > > registers are not accessible.
> >
> > I don't have a problem with skipping setting cmode writable if cmode is
> > not being changed. But hidden registers should be accessible regardless
> > of whether you are using single chip addressing mode or not. You need
> > to find why it isn't working for you, this is a bug.
>
> For the records, I read the above as requiring a fix the root cause, so
> I'm not applying this patch. Please correct me if I'm wrong.

You are correct. Sorry I forgot to reply to this thread after posting
the root cause fix.

For reference the root cause fix to the issue mentioned by this patch
is https://lore.kernel.org/netdev/20220425070454.348584-1-nathan@nathanross=
i.com/.

Thanks,
Nathan

>
> Thanks,
>
> Paolo
>