[PATCH 5.4 133/215] r8169: fix issue caused by buggy BIOS on certain boards with RTL8168d

Greg Kroah-Hartman
2024-04-11T10:20:33Z

From: Heiner Kallweit <hkallweit1@gmail.com>

commit 5d872c9f46bd2ea3524af3c2420a364a13667135 upstream.

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@vger.kernel.org
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/64f2055e-98b8-45ec-8568-665e3d54d4e6@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/realtek/r8169_main.c | 9 +++++++++
1 file changed, 9 insertions(+)

--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -6851,6 +6851,15 @@ static int r8169_mdio_register(struct rt
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;