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

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Message-Id: <20210212180010.221129-5-Shyam-sundar.S-k@amd.com>
Date:   Fri, 12 Feb 2021 23:30:10 +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: [PATCH 4/4] 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.

Signed-off-by: Sudheesh Mavila <sudheesh.mavila@....com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
index 1bb468ac9635..e328fd9bd294 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c
@@ -922,6 +922,12 @@ 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 */
+	reg = phy_read(phy_data->phydev, 0x00);
+	phy_write(phy_data->phydev, 0x00, reg | 0x8000);
+	read_poll_timeout(phy_read, reg, !(reg & 0x8000) || reg < 0,
+			  10000, 50000, true, phy_data->phydev, 0x0);
+
 	/* Disable RGMII mode */
 	phy_write(phy_data->phydev, 0x18, 0x7007);
 	reg = phy_read(phy_data->phydev, 0x18);
-- 
2.25.1