linux-kernel - Re: [PATCH net-next 1/2] net: phy: micrel: Move KSZ9477 errata fixes to PHY driver

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Message-ID: <9620f9f4-1d0f-45ed-b457-9a272af451f6@lunn.ch>
Date:   Sat, 3 Jun 2023 16:16:38 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Robert Hancock <robert.hancock@...ian.com>
Cc:     Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "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 <linux@...linux.org.uk>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] net: phy: micrel: Move KSZ9477 errata fixes
 to PHY driver

On Fri, Jun 02, 2023 at 05:40:18PM -0600, Robert Hancock wrote:
> The ksz9477 DSA switch driver is currently updating some MMD registers
> on the internal port PHYs to address some chip errata. However, these
> errata are really a property of the PHY itself, not the switch they are
> part of, so this is kind of a layering violation. It makes more sense for
> these writes to be done inside the driver which binds to the PHY and not
> the driver for the containing device.
> 
> This also addresses some issues where the ordering of when these writes
> are done may have been incorrect, causing the link to erratically fail to
> come up at the proper speed or at all. Doing this in the PHY driver
> during config_init ensures that they happen before anything else tries to
> change the state of the PHY on the port.
> 
> The new code also ensures that autonegotiation is disabled during the
> register writes and re-enabled afterwards, as indicated by the latest
> version of the errata documentation from Microchip.
> 
> Signed-off-by: Robert Hancock <robert.hancock@...ian.com>

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

    Andrew