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

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Message-ID: <Z0BpoCMcCQxTpbEb@shell.armlinux.org.uk>
Date: Fri, 22 Nov 2024 11:23:12 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: 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>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] net: phy: fix phy_ethtool_set_eee() incorrectly
 enabling LPI

On Fri, Nov 22, 2024 at 11:21:43AM +0000, 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
> 	Link partner 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.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> ---
>  drivers/net/phy/phy-c45.c |  2 +-
>  drivers/net/phy/phy.c     | 32 ++++++++++++++++++--------------
>  include/linux/phy.h       |  1 +
>  3 files changed, 20 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
> index 96d0b3a5a9d3..944ae98ad110 100644
> --- a/drivers/net/phy/phy-c45.c
> +++ b/drivers/net/phy/phy-c45.c
> @@ -1530,7 +1530,7 @@ int genphy_c45_ethtool_get_eee(struct phy_device *phydev,
>  		return ret;
>  
>  	data->eee_enabled = is_enabled;
> -	data->eee_active = ret;
> +	data->eee_active = phydev->eee_active;
>  	linkmode_copy(data->supported, phydev->supported_eee);
>  
>  	return 0;
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 4f3e742907cb..d03fe59cf1f3 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -990,14 +990,14 @@ static int phy_check_link_status(struct phy_device *phydev)
>  		phydev->state = PHY_RUNNING;
>  		err = genphy_c45_eee_is_active(phydev,
>  					       NULL, NULL, NULL);
> -		if (err <= 0)
> -			phydev->enable_tx_lpi = false;
> -		else
> -			phydev->enable_tx_lpi = phydev->eee_cfg.tx_lpi_enabled;
> +		phydev->eee_active = err <= 0;

Scrub that... this is inverted!

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