On Mon, Oct 27, 2025 at 01:57:48PM +0100, Emanuele Ghidoli wrote:
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.
We like to try to understand what is going on, and give accurate descriptions. You have given us important information here, which at minimum should go into the commit message, but more likely, it will help lead us to the correct fix.
So, two things here. You say:
I think that the phylink commit is just enabling by default the EEE support,
That needs confirming, because you are blaming the conversion to phylink, not that phylink now enabled EEE by default. Russell also tries to avoid behaviour change, which this clearly is. We want a better understanding what caused this behaviour change.
Also:
- Enabling EEE manually using ethtool, triggers the problem too (and ethtool
-show-eee report eee status enabled):
This indicates EEE has always been broken. This brokenness has been somewhat hidden in the past, and it is the change in behaviour in phylink which exposed this brokenness. A commit message using these words would be much more factually correct, and it would also fit with the Fixes: tag you used.
So, please work with Russell. I see two things which would be good to understand before a new version of the patch is submitted:
What cause the behaviour change such that EEE is now enabled? Was it deliberate? Should something be change to revert that behaviour change?
Given that EEE has always been broken, do we understand it sufficiently to say it is not fixable? Is there an errata? Are we sure it is the PHY and not the MAC which is broken?
Andrew