linux-kernel - Re: [RFC] net: dsa: slave: Advertise correct EEE capabilities at slave PHY setup

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Message-ID: <20230530164025.7a6d6bbd@wsk>
Date:   Tue, 30 May 2023 16:40:25 +0200
From:   Lukasz Majewski <lukma@...x.de>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     "Russell King (Oracle)" <linux@...linux.org.uk>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC] net: dsa: slave: Advertise correct EEE capabilities at
 slave PHY setup

Hi Andrew,

> On Tue, May 30, 2023 at 04:07:43PM +0200, Lukasz Majewski wrote:
> > Hi Russell,
> >   
> > > 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.
> > > > 
> > > > With DSA switch it also may happen that one would need to
> > > > disable EEE due to some network issues.
> > > > 
> > > > Corresponding switch DTS description:
> > > > 
> > > >  switch@0 {
> > > > 	 ports {
> > > > 		port@0 {
> > > > 		reg = <0>;
> > > > 		label = "lan1";
> > > > 		phy-handle = <&switchphy0>;
> > > > 		};
> > > > 	}
> > > > 	mdio {
> > > > 		switchphy0: switchphy@0 {
> > > > 		reg = <0>;
> > > > 		eee-broken-100tx;
> > > > 	};
> > > > 	};
> > > > 
> > > > This patch adjusts the content of MDIO_AN_EEE_ADV in MDIO_MMD_AN
> > > > "device" so the phydev->eee_broken_modes are taken into account
> > > > from the start of the slave PHYs.    
> > > 
> > > This should be handled by phylib today in recent kernels without
> > > the need for any patch (as I describe below, because the
> > > config_aneg PHY method should be programming it.) Are you seeing
> > > a problem with it in 6.4-rc?  
> > 
> > Unfortunately, for this project I use LTS 5.15.z kernel.
> > 
> > My impression is that the mv88e6xxx driver is not handling EEE setup
> > during initialization (even with v6.4-rc).  
> 
> In general, nearly every driver gets EEE wrong. 

Ach... I see :/

> I have a patchset
> which basically rewrites EEE.

Ok.

> It has been posted as RFC a couple
> times, and i plan to start posting it for merging this week.

Ok. :-)

> 
> But as a result, don't expect EEE to actually work with any LTS
> kernel.

Then, I think that it would be best to use the above "hack" until your
patch set is not reviewed and merged. After that, when customer will
mover forward with LTS kernel, I can test the EEE on the proper HW.

> 
> 	Andrew




Best regards,

Lukasz Majewski

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