[PATCH v3 1/2] net: phy: realtek: disable broadcast address feature of rtl8211f

[Zhiyuan Wan <kmlinuxm@gmail.com>]

This feature is enabled defaultly after a reset of this transceiver.
When this feature is enabled, the phy not only responds to the
configuration PHY address by pin states on board, but also responds
to address 0, the optional broadcast address of the MDIO bus.

But some MDIO device like mt7530 switch chip (integrated in mt7621
SoC), also use address 0 to configure a specific port, when use
mt7530 and rtl8211f together, it usually causes address conflict,
leads to the port of RTL8211FS stops working.

This patch disables broadcast address feature of rtl8211f, and
returns -ENODEV if using broadcast address (0) as phy address.

Reviewed-by: Yuki Lee <febrieac@outlook.com>
Signed-off-by: Zhiyuan Wan <kmlinuxm@gmail.com>
---
 drivers/net/phy/realtek.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
index f65d7f1f3..8a38b02ad 100644
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -31,6 +31,7 @@
 #define RTL8211F_PHYCR1				0x18
 #define RTL8211F_PHYCR2				0x19
 #define RTL8211F_INSR				0x1d
+#define RTL8211F_PHYAD0_EN			BIT(13)
 
 #define RTL8211F_LEDCR				0x10
 #define RTL8211F_LEDCR_MODE			BIT(15)
@@ -139,6 +140,17 @@ static int rtl821x_probe(struct phy_device *phydev)
 		return dev_err_probe(dev, PTR_ERR(priv->clk),
 				     "failed to get phy clock\n");
 
+	dev_dbg(dev, "disabling MDIO address 0 for this phy");
+	ret = phy_modify_paged_changed(phydev, 0xa43, RTL8211F_PHYCR1,
+				       RTL8211F_PHYAD0_EN, 0);
+	if (ret < 0) {
+		dev_err(dev, "disabling MDIO address 0 failed: %pe\n",
+			ERR_PTR(ret));
+	}
+	/* Don't allow using broadcast address as PHY address */
+	if (phydev->mdio.addr == 0)
+		return -ENODEV;
+
 	ret = phy_read_paged(phydev, 0xa43, RTL8211F_PHYCR1);
 	if (ret < 0)
 		return ret;
-- 
2.30.2