linux-kernel - Re: [PATCH net-next v1 3/4] net: phy: Don't report advertised EEE modes if EEE is disabled

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Message-ID: <aAo5HDLbpRhNIrn6@shell.armlinux.org.uk>
Date: Thu, 24 Apr 2025 14:14:04 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Oleksij Rempel <o.rempel@...gutronix.de>
Cc: Woojung Huh <woojung.huh@...rochip.com>, Andrew Lunn <andrew@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Heiner Kallweit <hkallweit1@...il.com>, kernel@...gutronix.de,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	UNGLinuxDriver@...rochip.com, Simon Horman <horms@...nel.org>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: Re: [PATCH net-next v1 3/4] net: phy: Don't report advertised EEE
 modes if EEE is disabled

On Thu, Apr 24, 2025 at 03:02:21PM +0200, Oleksij Rempel wrote:
> Currently, `ethtool --show-eee` reports "Advertised EEE link modes" even when
> EEE is disabled, which can be misleading. For example:
> 
>   EEE settings for lan1:
>           EEE status: disabled
>           Tx LPI: disabled
>           Supported EEE link modes:  100baseT/Full
>                                      1000baseT/Full
>           Advertised EEE link modes:  100baseT/Full
>                                       1000baseT/Full
>           Link partner advertised EEE link modes:  Not reported
> 
> This may lead to confusion for users who aren't familiar with kernel internals
> but understand that EEE functionality depends on proper advertisement during
> link negotiation. Seeing advertised EEE modes in this case might incorrectly
> suggest that EEE is still being advertised.
> 
> After this change, if EEE is disabled, the output becomes:
> 
>   EEE settings for lan1:
>           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:  Not reported
> 
> This better reflects the actual EEE configuration. The fix ensures
> advertised EEE modes are only reported when eee_cfg.eee_enabled is true.

No, this is a backwards step.

Tools like ethtool read-modify-write the settings. First they get, then
modify, then set.

This will have the effect that:

ethtool --set-eee eee off
ethtool --set-eee eee on

will clear the advertised link modes, which is not what one would
expect.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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