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@bootlin.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);
+		__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
-- 
2.49.0

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@bootlin.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