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Date:   Thu, 18 Aug 2022 17:13:51 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>,
        Russell King <rmk+kernel@armlinux.org.uk>
Cc:     netdev@vger.kernel.org, Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Russell King <linux@armlinux.org.uk>,
        Michael Grzeschik <m.grzeschik@pengutronix.de>,
        Oleksij Rempel <linux@rempel-privat.de>,
        Thorsten Leemhuis <regressions@leemhuis.info>,
        Alvin =?utf-8?Q?=C5=A0ipraga?= <alsi@bang-olufsen.dk>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Craig McQueen <craig@mcqueen.id.au>
Subject: Re: [PATCH net] net: dsa: microchip: keep compatibility with device
 tree blobs with no phy-mode
Message-ID: <Yv5XL4KTLxukVhck@lunn.ch>
References: <20220818143250.2797111-1-vladimir.oltean@nxp.com>
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> It is important to note that phy_device_create() initializes
> dev->interface = PHY_INTERFACE_MODE_GMII, and so, when we use
> phylink_create(PHY_INTERFACE_MODE_NA), no one will override this, and we
> will end up with a PHY_INTERFACE_MODE_GMII interface inherited from the
> PHY.

Is this actually a bug?

With pure phylib, you should call one of the connect functions, which
underneath calls phy_attach_direct() which has a phy_interface_t. So
the default in practice does not matter.

> All this means that in order to maintain compatibility with device tree
> blobs where the phy-mode property is missing, we need to allow the
> "gmii" phy-mode and treat it as "internal".

of_get_phy_mode() returns PHY_INTERFACE_MODE_NA if the property is
missing, which also suggests this is a bug.

I wonder if we have any ports which actually rely on
PHY_INTERFACE_MODE_GMII?

	 Andrew