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 <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20465
Signed-off-by: Christian Marangi <[email protected]>

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,

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;
 };