[openwrt/openwrt] kernel: rtl8261n: Add support for Serdes RX swap

[LEDE Commits]

ansuel pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/2b773bddeb7695076691e3247efcf0b604a2154a

commit 2b773bddeb7695076691e3247efcf0b604a2154a
Author: Richard Huynh <voxlympha at gmail.com>
AuthorDate: Sun Oct 19 21:52:59 2025 +1100

    kernel: rtl8261n: Add support for Serdes RX swap
    
    Datasheet claims this register bit is supposed to be set by default,
    however it was found in practice to not be, and OEM drivers would set
    this bit at the same time.
    
    Signed-off-by: Richard Huynh <voxlympha at gmail.com>
    Link: https://github.com/openwrt/openwrt/pull/20465
    Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phy.c    | 6 ++++++
 target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phylib.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phy.c b/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phy.c
index faa057f029..a1eb2c1614 100644
--- a/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phy.c
+++ b/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phy.c
@@ -61,6 +61,7 @@ static int rtl826xb_probe(struct phy_device *phydev)
 
     priv->phytype = (phydev->drv->phy_id == REALTEK_PHY_ID_RTL8261N) ? (RTK_PHYLIB_RTL8261N) : (RTK_PHYLIB_RTL8264B);
     priv->isBasePort = (phydev->drv->phy_id == REALTEK_PHY_ID_RTL8261N) ? (1) : (((phydev->mdio.addr % 4) == 0) ? (1) : (0));
+    priv->pnswap_rx = device_property_read_bool(dev, "realtek,pnswap-rx");
     priv->pnswap_tx = device_property_read_bool(dev, "realtek,pnswap-tx");
     phydev->priv = priv;
 
@@ -125,6 +126,11 @@ static int rtkphy_config_init(struct phy_device *phydev)
             }
           #endif
 
+            if (priv->pnswap_rx)
+                phy_set_bits_mmd(phydev, MDIO_MMD_VEND1,
+                                 REALTEK_SERDES_GLOBAL_CFG,
+                                 REALTEK_HSI_INV);
+
             if (priv->pnswap_tx)
                 phy_set_bits_mmd(phydev, MDIO_MMD_VEND1,
                                  REALTEK_SERDES_GLOBAL_CFG,
diff --git a/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phylib.h b/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phylib.h
index c94e9cb966..c1253b1ec9 100644
--- a/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phylib.h
+++ b/target/linux/generic/files/drivers/net/phy/rtl8261n/rtk_phylib.h
@@ -51,6 +51,7 @@ struct rtk_phy_priv {
     uint8 isBasePort;
     rt_phy_patch_db_t *patch;
 
+    bool pnswap_rx;
     bool pnswap_tx;
 };