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

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Date: Tue, 30 May 2023 16:23:20 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Lukasz Majewski <lukma@...x.de>
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

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. I have a patchset
which basically rewrites EEE. It has been posted as RFC a couple
times, and i plan to start posting it for merging this week.

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

	Andrew