[PATCH 5.4 068/340] net: amd-xgbe: Fix network fluctuations when using 1G BELFUSE SFP

[Greg Kroah-Hartman]

From: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>

[ Upstream commit 9eab3fdb419916f66a72d1572f68d82cd9b3f963 ]

Frequent link up/down events can happen when a Bel Fuse SFP part is
connected to the amd-xgbe device. Try to avoid the frequent link
issues by resetting the PHY as documented in Bel Fuse SFP datasheets.

Fixes: e722ec82374b ("amd-xgbe: Update the BelFuse quirk to support SGMII")
Co-developed-by: Sudheesh Mavila <sudheesh.mavila@xxxxxxx>
Signed-off-by: Sudheesh Mavila <sudheesh.mavila@xxxxxxx>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
Acked-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
index 387d3aeebf237..d6f6afb67bcc6 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
@@ -921,6 +921,9 @@ static bool xgbe_phy_belfuse_phy_quirks(struct xgbe_prv_data *pdata)
 	if ((phy_id & 0xfffffff0) != 0x03625d10)
 		return false;
 
+	/* Reset PHY - wait for self-clearing reset bit to clear */
+	genphy_soft_reset(phy_data->phydev);
+
 	/* Disable RGMII mode */
 	phy_write(phy_data->phydev, 0x18, 0x7007);
 	reg = phy_read(phy_data->phydev, 0x18);
-- 
2.27.0