netdev - Re: [PATCH net v3] net: phy: fix phy_ethtool_set

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Message-ID: <bedf2521-dcbf-4b5b-8482-9436a54a614f@redhat.com>
Date: Thu, 28 Nov 2024 09:44:37 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
 Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Oleksij Rempel <o.rempel@...gutronix.de>,
 Florian Fainelli <florian.fainelli@...adcom.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net v3] net: phy: fix phy_ethtool_set_eee() incorrectly
 enabling LPI

Hi,

On 11/23/24 15:50, Russell King (Oracle) wrote:
> When phy_ethtool_set_eee_noneg() detects a change in the LPI
> parameters, it attempts to update phylib state and trigger the link
> to cycle so the MAC sees the updated parameters.
> 
> However, in doing so, it sets phydev->enable_tx_lpi depending on
> whether the EEE configuration allows the MAC to generate LPI without
> taking into account the result of negotiation.
> 
> This can be demonstrated with a 1000base-T FD interface by:
> 
>  # ethtool --set-eee eno0 advertise 8   # cause EEE to be not negotiated
>  # ethtool --set-eee eno0 tx-lpi off
>  # ethtool --set-eee eno0 tx-lpi on
> 
> This results in being true, despite EEE not having been negotiated and:
>  # ethtool --show-eee eno0
> 	EEE status: enabled - inactive
> 	Tx LPI: 250 (us)
> 	Supported EEE link modes:  100baseT/Full
> 	                           1000baseT/Full
> 	Advertised EEE link modes:  100baseT/Full
> 	                                         1000baseT/Full
> 
> Fix this by keeping track of whether EEE was negotiated via a new
> eee_active member in struct phy_device, and include this state in
> the decision whether phydev->enable_tx_lpi should be set.
> 
> Fixes: 3e43b903da04 ("net: phy: Immediately call adjust_link if only tx_lpi_enabled changes")
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

This patch did not apply net cleanly to net tree when it was submitted,
due to its dependency. As a result it did not went through the CI tests.
Currently there is little material there phy specific - mostly builds
with different Kconfigs - but with time we hope to increase H/W coverage.

AFAICS this patch has no kconfig implication, so my local build should
be a safe-enough test, but please wait for the pre-reqs being merged for
future submissions.

Thanks,

Paolo