netdev - [PATCH net] r8169: fix issue caused by buggy BIOS on certain boards with RTL8168d

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Message-ID: <64f2055e-98b8-45ec-8568-665e3d54d4e6@gmail.com>
Date: Sat, 30 Mar 2024 12:49:02 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: Realtek linux nic maintainers <nic_swsd@...ltek.com>,
 Paolo Abeni <pabeni@...hat.com>, David Miller <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net] r8169: fix issue caused by buggy BIOS on certain boards
 with RTL8168d

On some boards with this chip version the BIOS is buggy and misses
to reset the PHY page selector. This results in the PHY ID read
accessing registers on a different page, returning a more or
less random value. Fix this by resetting the page selector first.

Fixes: f1e911d5d0df ("r8169: add basic phylib support")
Cc: stable@...r.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 5c879a5c8..3936db3d4 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -5141,6 +5141,15 @@ static int r8169_mdio_register(struct rtl8169_private *tp)
 	struct mii_bus *new_bus;
 	int ret;
 
+	/* On some boards with this chip version the BIOS is buggy and misses
+	 * to reset the PHY page selector. This results in the PHY ID read
+	 * accessing registers on a different page, returning a more or
+	 * less random value. Fix this by resetting the page selector first.
+	 */
+	if (tp->mac_version == RTL_GIGA_MAC_VER_25 ||
+	    tp->mac_version == RTL_GIGA_MAC_VER_26)
+		r8169_mdio_write(tp, 0x1f, 0);
+
 	new_bus = devm_mdiobus_alloc(&pdev->dev);
 	if (!new_bus)
 		return -ENOMEM;
-- 
2.44.0