netdev - Re: [PATCH net-next v1 2/4] net: phy: micrel: add EEE configuration support for KSZ9477 variants of PHYs

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Message-ID: <20230120055514.GI6162@pengutronix.de>
Date:   Fri, 20 Jan 2023 06:55:14 +0100
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...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>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Arun.Ramadoss@...rochip.com
Subject: Re: [PATCH net-next v1 2/4] net: phy: micrel: add EEE configuration
 support for KSZ9477 variants of PHYs

On Thu, Jan 19, 2023 at 11:25:42AM -0800, Florian Fainelli wrote:
> 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).

It will work for this PHY, but not allow to complete support for AR8035.
AR8035 provides support for "SmartEEE" where  tx_lpi_enabled and
tx_lpi_timer are optionally handled by the PHY, not by MAC.

Regards,
Oleksij
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