generic: fix probe issues with RealTek RTL8221B PHYs with kernel 6.6

Author: coolsnowwolf

target/linux/generic/backport-6.6/781-13-v6.11-net-phy-realtek-mark-existing-MMDs-as-present.patch

@@ -0,0 +1,27 @@
+From 1addfb042a9d27788a0fb2c2935045b56fd8560e Mon Sep 17 00:00:00 2001
+From: Daniel Golle <daniel@makrotopia.org>
+Date: Thu, 23 Jan 2025 03:25:29 +0000
+Subject: [PATCH] net: phy: realtek: mark existing MMDs as present
+
+When using Clause-45 mode to access RealTek RTL8221B 2.5G PHYs some
+versions of the PHY fail to report the MMDs present on the PHY.
+Mark MMDs PMAPMD, PCS and AN which are always existing according to
+the datasheet as present to fix that.
+
+Signed-off-by: Daniel Golle <daniel@makrotopia.org>
+---
+ /drivers/net/phy/realtek.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/drivers/net/phy/realtek.c
++++ b/drivers/net/phy/realtek.c
+@@ -1034,6 +1034,9 @@ static int rtl822x_c45_get_features(stru
+ 	linkmode_set_bit(ETHTOOL_LINK_MODE_TP_BIT,
+ 			 phydev->supported);
+ 
++	phydev->c45_ids.mmds_present |= MDIO_DEVS_PMAPMD | MDIO_DEVS_PCS |
++				        MDIO_DEVS_AN;
++
+ 	return genphy_c45_pma_read_abilities(phydev);
+ }
+