linux-kernel - [PATCH 5.0 033/146] net: phy: dont clear BMCR in genphy_soft

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Message-Id: <20190401170051.315584721@linuxfoundation.org>
Date:   Mon,  1 Apr 2019 19:00:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Phil Reid <preid@...ctromag.com.au>,
        liweihang <liweihang@...ilicon.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.0 033/146] net: phy: dont clear BMCR in genphy_soft_reset

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Heiner Kallweit <hkallweit1@...il.com>

[ Upstream commit d29f5aa0bc0c321e1b9e4658a2a7e08e885da52a ]

So far we effectively clear the BMCR register. Some PHY's can deal
with this (e.g. because they reset BMCR to a default as part of a
soft-reset) whilst on others this causes issues because e.g. the
autoneg bit is cleared. Marvell is an example, see also thread [0].
So let's be a little bit more gentle and leave all bits we're not
interested in as-is. This change is needed for PHY drivers to
properly deal with the original patch.

[0] https://marc.info/?t=155264050700001&r=1&w=2

Fixes: 6e2d85ec0559 ("net: phy: Stop with excessive soft reset")
Tested-by: Phil Reid <preid@...ctromag.com.au>
Tested-by: liweihang <liweihang@...ilicon.com>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/phy/phy_device.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1827,7 +1827,7 @@ int genphy_soft_reset(struct phy_device
 {
 	int ret;
 
-	ret = phy_write(phydev, MII_BMCR, BMCR_RESET);
+	ret = phy_set_bits(phydev, MII_BMCR, BMCR_RESET);
 	if (ret < 0)
 		return ret;