linux-kernel - Re: [PATCH net-next v5 03/13] net: phy: phy_port: Correctly recompute the port's linkmodes

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Message-ID: <31bde1a4-adaf-4a1d-8b88-6075189a6af4@kernel.org>
Date: Wed, 11 Feb 2026 10:39:54 +0100
From: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
To: Maxime Chevallier <maxime.chevallier@...tlin.com>, davem@...emloft.net,
 Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Russell King <linux@...linux.org.uk>, Heiner Kallweit <hkallweit1@...il.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 thomas.petazzoni@...tlin.com, Herve Codina <herve.codina@...tlin.com>,
 Florian Fainelli <f.fainelli@...il.com>,
 Vladimir Oltean <vladimir.oltean@....com>,
 Köry Maincent <kory.maincent@...tlin.com>,
 Marek Behún <kabel@...nel.org>,
 Oleksij Rempel <o.rempel@...gutronix.de>,
 Nicolò Veronese <nicveronese@...il.com>,
 Simon Horman <horms@...nel.org>, mwojtas@...omium.org,
 Romain Gantois <romain.gantois@...tlin.com>,
 Daniel Golle <daniel@...rotopia.org>,
 Dimitri Fedrau <dimitri.fedrau@...bherr.com>
Subject: Re: [PATCH net-next v5 03/13] net: phy: phy_port: Correctly recompute
 the port's linkmodes



Le 05/02/2026 à 10:23, Maxime Chevallier a écrit :
> a PHY-driven phy_port contains a 'supported' field containing the
> linkmodes available on this port. This is populated based on :
>   - The PHY's reported features
>   - The DT representation of the connector
>   - The PHY's attach_mdi() callback
> 
> As these different attrbution methods work in conjunction, the helper
> phy_port_update_supported() recomputes the final 'supported' value based
> on the populated mediums, linkmodes and pairs.
> 
> However this recompute wasn't correctly implemented, and added more
> modes than necessary by or'ing the medium-specific modes to the existing
> support. Let's fix this and properly filter the modes.
> 
> Fixes: 589e934d2735 ("net: phy: Introduce PHY ports representation")
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>

Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@...nel.org>

> ---
>   drivers/net/phy/phy_port.c | 24 +++++++++++++++++-------
>   1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_port.c b/drivers/net/phy/phy_port.c
> index a269e9ea12c4..63d1bb154dc7 100644
> --- a/drivers/net/phy/phy_port.c
> +++ b/drivers/net/phy/phy_port.c
> @@ -108,16 +108,10 @@ EXPORT_SYMBOL_GPL(phy_of_parse_port);
>    */
>   void phy_port_update_supported(struct phy_port *port)
>   {
> -	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported) = { 0 };
> +	__ETHTOOL_DECLARE_LINK_MODE_MASK(supported) = {0};
>   	unsigned long mode;
>   	int i;
>   
> -	for_each_set_bit(i, &port->mediums, __ETHTOOL_LINK_MEDIUM_LAST) {
> -		linkmode_zero(supported);
> -		phy_caps_medium_get_supported(supported, i, port->pairs);
> -		linkmode_or(port->supported, port->supported, supported);
> -	}
> -
>   	/* If there's no pairs specified, we grab the default number of
>   	 * pairs as the max of the default pairs for each linkmode
>   	 */
> @@ -127,6 +121,22 @@ void phy_port_update_supported(struct phy_port *port)
>   			port->pairs = max_t(int, port->pairs,
>   					    ethtool_linkmode_n_pairs(mode));
>   
> +	for_each_set_bit(i, &port->mediums, __ETHTOOL_LINK_MEDIUM_LAST) {
> +		__ETHTOOL_DECLARE_LINK_MODE_MASK(med_supported) = {0};
> +
> +		phy_caps_medium_get_supported(med_supported, i, port->pairs);
> +		linkmode_or(supported, supported, med_supported);
> +	}
> +
> +	/* If port->supported is already populated, filter it out with the
> +	 * medium/pair support. Otherwise, let's just use this medium-based
> +	 * support as the port's supported list.
> +	 */
> +	if (linkmode_empty(port->supported))
> +		linkmode_copy(port->supported, supported);
> +	else
> +		linkmode_and(port->supported, supported, port->supported);
> +
>   	/* Serdes ports supported through SFP may not have any medium set,
>   	 * as they will output PHY_INTERFACE_MODE_XXX modes. In that case, derive
>   	 * the supported list based on these interfaces