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Date:   Thu, 19 Jan 2023 11:25:42 -0800
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Subject: Re: [PATCH net-next v1 2/4] net: phy: micrel: add EEE configuration
 support for KSZ9477 variants of PHYs
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To:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com, Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@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>
Cc:     kernel@pengutronix.de, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, Arun.Ramadoss@microchip.com
References: <20230119131821.3832456-1-o.rempel@pengutronix.de>
 <20230119131821.3832456-3-o.rempel@pengutronix.de>
From:   Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <20230119131821.3832456-3-o.rempel@pengutronix.de>
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On 1/19/23 05:18, Oleksij Rempel wrote:
> KSZ9477 variants of PHYs are not completely compatible with generic
> phy_ethtool_get/set_eee() handlers. For example MDIO_PCS_EEE_ABLE acts
> like a mirror of MDIO_AN_EEE_ADV register. If MDIO_AN_EEE_ADV set to 0,
> MDIO_PCS_EEE_ABLE will be 0 too. It means, if we do
> "ethtool --set-eee lan2 eee off", we won't be able to enable it again.
> 
> With this patch, instead of reading MDIO_PCS_EEE_ABLE register, the
> driver will provide proper abilities.

We have hooks in place already for PHY drivers with the form of the 
read_mmd and write_mmd callbacks, did this somehow not work for you?

Below is an example:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d88fd1b546ff19c8040cfaea76bf16aed1c5a0bb

(here the register location is non-standard but the bit definitions 
within that register are following the standard).
-- 
Florian