[PATCH 4.19 62/79] r8169: fix wrong PHY ID issue with RTL8168dp

[Greg Kroah-Hartman]

From: Heiner Kallweit <hkallweit1@xxxxxxxxx>

[ Upstream commit 62bdc8fd1c21d4263ebd18bec57f82532d09249f ]

As reported in [0] at least one RTL8168dp version has problems
establishing a link. This chip version has an integrated RTL8211b PHY,
however the chip seems to report a wrong PHY ID, resulting in a wrong
PHY driver (for Generic Realtek PHY) being loaded.
Work around this issue by adding a hook to r8168dp_2_mdio_read()
for returning the correct PHY ID.

[0] https://bbs.archlinux.org/viewtopic.php?id=246508

Fixes: 242cd9b5866a ("r8169: use phy_resume/phy_suspend")
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/realtek/r8169.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -1010,6 +1010,10 @@ static int r8168dp_2_mdio_read(struct rt
 {
 	int value;
 
+	/* Work around issue with chip reporting wrong PHY ID */
+	if (reg == MII_PHYSID2)
+		return 0xc912;
+
 	r8168dp_2_mdio_start(tp);
 
 	value = r8169_mdio_read(tp, reg);