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Date:   Tue, 30 May 2023 15:40:39 +0200
From:   Lukasz Majewski <lukma@denx.de>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Russell King <linux@armlinux.org.uk>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC] net: dsa: slave: Advertise correct EEE capabilities at
 slave PHY setup
Message-ID: <20230530154039.4552e08a@wsk>
In-Reply-To: <32aa2c0f-e284-4c5e-ba13-a2ea7783c202@lunn.ch>
References: <20230530122621.2142192-1-lukma@denx.de>
        <32aa2c0f-e284-4c5e-ba13-a2ea7783c202@lunn.ch>
Organization: denx.de
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Hi Andrew,

> On Tue, May 30, 2023 at 02:26:21PM +0200, Lukasz Majewski wrote:
> > One can disable in device tree advertising of EEE capabilities of
> > PHY when 'eee-broken-100tx' property is present in DTS.
> >=20
> > With DSA switch it also may happen that one would need to disable
> > EEE due to some network issues. =20
>=20
> Is EEE actually broken in the MAC/PHY combination?
>=20

Problem is that when I connect on this project some non-manageable
switches (which by default have EEE enabled), then I observe very rare
and sporadic link loss and reconnection.

Disabling EEE solves the problem.

> You should not be using this DT option for configuration. It is there
> because there is some hardware which is truly broken, and needs EEE
> turned off.

Yes, I do think that the above sentence sums up my use case.

>=20
> If EEE does work, but you need to turn it off because of latency etc,
> then please use ethtool.
>=20

Yes, correct - it is possible to disable the EEE with=20

ethtool --set-eee lan2 eee off

However, as I've stated in the mail, I cannot re-enable EEE once
disabled with:

ethtool --set-eee lan2 eee on

ethtool --show-eee lan2
EEE Settings for lan2:
        EEE status: not supported


As the capability register shows value of 0.

>      Andrew,


Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

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