linux-kernel - Re: [PATCH net-next v4 03/13] net: phy: phy_port: Correctly recompute the port's linkmodes

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Message-ID: <8d6a8d0a-77e1-47cd-8562-ae852e22a62a@bootlin.com>
Date: Wed, 4 Feb 2026 08:39:28 +0100
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: 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, Christophe Leroy
 <christophe.leroy@...roup.eu>, 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 v4 03/13] net: phy: phy_port: Correctly recompute
 the port's linkmodes



On 03/02/2026 18:28, Maxime Chevallier wrote:
> 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>
> ---
>  drivers/net/phy/phy_port.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_port.c b/drivers/net/phy/phy_port.c
> index a269e9ea12c4..ad2580529842 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 +121,23 @@ 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) {
> +		pr_info("Adding mode for medium %d pairs %d\n", i, port->pairs);

Bah. That print statement doesn't belong here...

Maxime