linux-kernel - [RFC PATCH net] net: phy: Fix "link partner" information disappear issue

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Date:   Thu, 10 Oct 2019 17:30:08 +0800
From:   Yonglong Liu <liuyonglong@...wei.com>
To:     <davem@...emloft.net>, <hkallweit1@...il.com>, <andrew@...n.ch>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <salil.mehta@...wei.com>,
        <yisen.zhuang@...wei.com>, <shiju.jose@...wei.com>
Subject: [RFC PATCH net] net: phy: Fix "link partner" information disappear issue

Some drivers just call phy_ethtool_ksettings_set() to set the
links, for those phy drivers that use genphy_read_status(), if
autoneg is on, and the link is up, than execute "ethtool -s
ethx autoneg on" will cause "link partner" information disappear.

The call trace is phy_ethtool_ksettings_set()->phy_start_aneg()
->linkmode_zero(phydev->lp_advertising)->genphy_read_status(),
the link didn't change, so genphy_read_status() just return, and
phydev->lp_advertising is zero now.

This patch call genphy_read_lpa() before the link state judgement
to fix this problem.

Fixes: 88d6272acaaa ("net: phy: avoid unneeded MDIO reads in genphy_read_status")
Signed-off-by: Yonglong Liu <liuyonglong@...wei.com>
---
 drivers/net/phy/phy_device.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 9d2bbb1..ef3073c 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1839,6 +1839,10 @@ int genphy_read_status(struct phy_device *phydev)
 	if (err)
 		return err;
 
+	err = genphy_read_lpa(phydev);
+	if (err < 0)
+		return err;
+
 	/* why bother the PHY if nothing can have changed */
 	if (phydev->autoneg == AUTONEG_ENABLE && old_link && phydev->link)
 		return 0;
@@ -1848,10 +1852,6 @@ int genphy_read_status(struct phy_device *phydev)
 	phydev->pause = 0;
 	phydev->asym_pause = 0;
 
-	err = genphy_read_lpa(phydev);
-	if (err < 0)
-		return err;
-
 	if (phydev->autoneg == AUTONEG_ENABLE && phydev->autoneg_complete) {
 		phy_resolve_aneg_linkmode(phydev);
 	} else if (phydev->autoneg == AUTONEG_DISABLE) {
-- 
2.8.1