netdev - [net,v2, 4/4] net: amd-xgbe: Fix network fluctuations when using 1G BELFUSE SFP

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Date:   Wed, 17 Feb 2021 00:37:10 +0530
From:   Shyam Sundar S K <Shyam-sundar.S-k@....com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     Sudheesh.Mavila@....com,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Sudheesh Mavila <sudheesh.mavila@....com>
Subject: [net,v2, 4/4] net: amd-xgbe: Fix network fluctuations when using 1G BELFUSE SFP

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@....com>
Signed-off-by: Sudheesh Mavila <sudheesh.mavila@....com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
Acked-by: Tom Lendacky <thomas.lendacky@....com>
---
v1->v2:
- Add Co-Developed-by: and Fixes: tag
- Use genphy_soft_reset() as suggested by Florian.

 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 d3f72faecd1d..18e48b3bc402 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
@@ -922,6 +922,9 @@ 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);
-- 
2.25.1