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Date:   Mon, 25 Apr 2022 01:16:38 +0200
From:   Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Nathan Rossi <nathan@nathanrossi.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        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>,
        Paolo Abeni <pabeni@redhat.com>
Subject: Re: [PATCH v2] net: dsa: mv88e6xxx: Fix port_hidden_wait to account
 for port_base_addr
Message-ID: <20220425011638.70065c7b@thinkpad>
In-Reply-To: <YmXQK7Wzb1GDxwRP@lunn.ch>
References: <20220424153143.323338-1-nathan@nathanrossi.com>
        <YmWkgkILCrBP5hRG@lunn.ch>
        <20220424213359.246cd5ab@thinkpad>
        <YmXQK7Wzb1GDxwRP@lunn.ch>
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On Mon, 25 Apr 2022 00:33:15 +0200
Andrew Lunn <andrew@lunn.ch> wrote:

> On Sun, Apr 24, 2022 at 09:33:59PM +0200, Marek Beh=C3=BAn wrote:
> > On Sun, 24 Apr 2022 21:26:58 +0200
> > Andrew Lunn <andrew@lunn.ch> wrote:
> >  =20
> > > On Sun, Apr 24, 2022 at 03:31:43PM +0000, Nathan Rossi wrote: =20
> > > > The other port_hidden functions rely on the port_read/port_write
> > > > functions to access the hidden control port. These functions apply =
the
> > > > offset for port_base_addr where applicable. Update port_hidden_wait=
 to
> > > > use the port_wait_bit so that port_base_addr offsets are accounted =
for
> > > > when waiting for the busy bit to change.
> > > >=20
> > > > Without the offset the port_hidden_wait function would timeout on
> > > > devices that have a non-zero port_base_addr (e.g. MV88E6141), howev=
er
> > > > devices that have a zero port_base_addr would operate correctly (e.=
g.
> > > > MV88E6390).
> > > >=20
> > > > Fixes: ea89098ef9a5 ("net: dsa: mv88x6xxx: mv88e6390 errata")   =20
> > >=20
> > > That is further back than needed. And due to the code moving around
> > > and getting renamed, you are added extra burden on those doing the
> > > back port for no actual gain.
> > >=20
> > > Please verify what i suggested, 609070133aff1 is better and then
> > > repost. =20
> >=20
> > The bug was introduced by ea89098ef9a5. =20
>=20
> I have to disagree with that. ea89098ef9a5 adds:
>=20
> mv88e6390_hidden_wait()
>=20
> The mv88e6390_ means it should be used with the mv88e6390 family. And
> all members of that family have port offset 0. There is no bug here.
>=20
> 609070133aff1 renames it to mv88e6xxx_port_hidden_wait(). It now has
> the generic mv88e6xxx_ prefix, so we can expect it to work with any
> device. But it does not. This is where the bug has introduced.

You are right. My bad, sorry.

Marek