netdev - Re: [PATCH v1] net: phy: dp83867: Disable EEE support as not implemented

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Message-ID: <664ef58b-d7e6-4f08-b88f-e7c2cf08c83c@gmail.com>
Date: Mon, 27 Oct 2025 13:57:48 +0100
From: Emanuele Ghidoli <ghidoliemanuele@...il.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
 Emanuele Ghidoli <emanuele.ghidoli@...adex.com>,
 Russell King <linux@...linux.org.uk>,
 Oleksij Rempel <o.rempel@...gutronix.de>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v1] net: phy: dp83867: Disable EEE support as not
 implemented



On 27/10/2025 00:45, Andrew Lunn wrote:
>> Since the introduction of phylink-managed EEE support in the stmmac driver,
>> EEE is now enabled by default, leading to issues on systems using the
>> DP83867 PHY.
> 
> Did you do a bisect to prove this?
Yes, I have done a bisect and the commit that introduced the behavior on our
board is 4218647d4556 ("net: stmmac: convert to phylink managed EEE support").

> 
>> Fixes: 2a10154abcb7 ("net: phy: dp83867: Add TI dp83867 phy")
> 
> What has this Fixes: tag got to do with phylink?
I think that the phylink commit is just enabling by default the EEE support,
and my commit is not really fixing that. It is why I didn't put a Fixes: tag
pointing to that.

I’ve tried to trace the behavior, but it’s quite complex. From my testing, I
can summarize the situation as follows:

- ethtool, after that patch, returns:
ethtool --show-eee end0
EEE settings for end0:
        EEE status: enabled - active
        Tx LPI: 1000000 (us)
        Supported EEE link modes:  100baseT/Full
                                   1000baseT/Full
        Advertised EEE link modes:  100baseT/Full
                                    1000baseT/Full
        Link partner advertised EEE link modes:  100baseT/Full
                                                 1000baseT/Full
- before that patch returns, after boot:
EEE settings for end0:
        EEE status: disabled
        Tx LPI: disabled
        Supported EEE link modes:  100baseT/Full
                                   1000baseT/Full
        Advertised EEE link modes:  Not reported
        Link partner advertised EEE link modes:  100baseT/Full
                                                 1000baseT/Full
- Enabling EEE manually using ethtool, triggers the problem too (and ethtool
-show-eee report eee status enabled):
ethtool --set-eee end0 eee on tx-lpi on
ethtool --show-eee end0
EEE settings for end0:
        EEE status: enabled - active
        Tx LPI: 1000000 (us)
        Supported EEE link modes:  100baseT/Full
                                   1000baseT/Full
        Advertised EEE link modes:  100baseT/Full
                                    1000baseT/Full
        Link partner advertised EEE link modes:  100baseT/Full
                                                 1000baseT/Full

I understand Russell point of view but from my point of view EEE is now
enabled by default, and before it wasn't, at least on my setup.

> 
> I hope you have seen Russell is not so happy you claim phylink is to
> blame here...
> 
> 	Andrew
>  

Emanuele