netdev - Re: [PATCH v2 net] net: mdio-mux: fix C45 access returning -EIO after API change

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Message-ID: <85415327-2b1f-40bc-becc-c3c7332fe95d@lunn.ch>
Date: Wed, 18 Oct 2023 20:12:07 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Vladimir Oltean <vladimir.oltean@....com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	Florian Fainelli <f.fainelli@...il.com>,
	Michael Walle <michael@...le.cc>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net] net: mdio-mux: fix C45 access returning -EIO
 after API change

On Tue, Oct 17, 2023 at 05:31:44PM +0300, Vladimir Oltean wrote:
> The mii_bus API conversion to read_c45() and write_c45() did not cover
> the mdio-mux driver before read() and write() were made C22-only.
> 
> This broke arch/arm64/boot/dts/freescale/fsl-ls1028a-qds-13bb.dtso.
> The -EOPNOTSUPP from mdiobus_c45_read() is transformed by
> get_phy_c45_devs_in_pkg() into -EIO, is further propagated to
> of_mdiobus_register() and this makes the mdio-mux driver fail to probe
> the entire child buses, not just the PHYs that cause access errors.
> 
> Fix the regression by introducing special c45 read and write accessors
> to mdio-mux which forward the operation to the parent MDIO bus.
> 
> Fixes: db1a63aed89c ("net: phy: Remove fallback to old C45 method")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew