linux-kernel - [PATCH 5.12 042/110] net: phy: dp83867: perform soft reset and retain established link

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Message-Id: <20210628141828.31757-43-sashal@kernel.org>
Date:   Mon, 28 Jun 2021 10:17:20 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Praneeth Bajjuri <praneeth@...com>, Geet Modi <geet.modi@...com>,
        Andrew Lunn <andrew@...n.ch>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 042/110] net: phy: dp83867: perform soft reset and retain established link

From: Praneeth Bajjuri <praneeth@...com>

[ Upstream commit da9ef50f545f86ffe6ff786174d26500c4db737a ]

Current logic is performing hard reset and causing the programmed
registers to be wiped out.

as per datasheet: https://www.ti.com/lit/ds/symlink/dp83867cr.pdf
8.6.26 Control Register (CTRL)

do SW_RESTART to perform a reset not including the registers,
If performed when link is already present,
it will drop the link and trigger re-auto negotiation.

Signed-off-by: Praneeth Bajjuri <praneeth@...com>
Signed-off-by: Geet Modi <geet.modi@...com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/phy/dp83867.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index 9bd9a5c0b1db..6bbc81ad295f 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -826,16 +826,12 @@ static int dp83867_phy_reset(struct phy_device *phydev)
 {
 	int err;
 
-	err = phy_write(phydev, DP83867_CTRL, DP83867_SW_RESET);
+	err = phy_write(phydev, DP83867_CTRL, DP83867_SW_RESTART);
 	if (err < 0)
 		return err;
 
 	usleep_range(10, 20);
 
-	/* After reset FORCE_LINK_GOOD bit is set. Although the
-	 * default value should be unset. Disable FORCE_LINK_GOOD
-	 * for the phy to work properly.
-	 */
 	return phy_modify(phydev, MII_DP83867_PHYCTRL,
 			 DP83867_PHYCR_FORCE_LINK_GOOD, 0);
 }
-- 
2.30.2