openwrt/target/linux/generic/pending-6.6/706-net-phy-populate-host_interfaces-when-attaching-PHY.patch

From 9e1a0d2006bc108b239b5bc00b42c2a8cc651217 Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Tue, 8 Oct 2024 23:58:41 +0100
Subject: [PATCH] net: phy: populate host_interfaces when attaching PHY

Use bitmask of interfaces supported by the MAC for the PHY to choose
from if the declared interface mode is among those using a single pair
of SerDes lanes.
This will allow 2500Base-T PHYs to switch to SGMII on most hosts, which
results in half-duplex being supported in case the MAC supports them.
Without this change, 2500Base-T PHYs will always operate in 2500Base-X
mode with rate-matching, which is not only wasteful in terms of energy
consumption, but also limits the supported interface modes to
full-duplex only.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/phy/phylink.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -2044,6 +2044,13 @@ int phylink_fwnode_phy_connect(struct ph
 		pl->link_config.interface = pl->link_interface;
 	}
 
+	/* Assume SerDes interface modes share the same lanes and allow
+	 * the PHY to switch between them
+	 */
+	if (test_bit(pl->link_interface, phylink_sfp_interfaces))
+		phy_interface_and(phy_dev->host_interfaces, phylink_sfp_interfaces,
+				  pl->config->supported_interfaces);
+
 	ret = phy_attach_direct(pl->netdev, phy_dev, flags,
 				pl->link_interface);
 	phy_device_free(phy_dev);