net: phy: fix duplex out of sync problem while changing settings

mainline inclusion
from mainline
commit: a4db9055
category: bugfix
bugzilla: 185671 https://gitee.com/openeuler/kernel/issues/I4DDEL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a4db9055fdb9cf607775c66d39796caf6439ec92

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

As reported by Zhang there's a small issue if in forced mode the duplex
mode changes with the link staying up [0]. In this case the MAC isn't
notified about the change.

The proposed patch relies on the phylib state machine and ignores the
fact that there are drivers that uses phylib but not the phylib state
machine. So let's don't change the behavior for such drivers and fix
it w/o re-adding state PHY_FORCING for the case that phylib state
machine is used.

[0] https://lore.kernel.org/netdev/a5c26ffd-4ee4-a5e6-4103-873208ce0dc5@huawei.com/T/

Fixes: 2bd229df ("net: phy: remove state PHY_FORCING")
Reported-by: NZhang Changzhong <zhangchangzhong@huawei.com>
Tested-by: NZhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/7b8b9456-a93f-abbc-1dc5-a2c2542f932c@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NZhang Changzhong <zhangchangzhong@huawei.com>
Reviewed-by: NWei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/net/phy/phy.c

@@ -831,7 +831,12 @@ int phy_ethtool_ksettings_set(struct phy_device *phydev,
 	phydev->mdix_ctrl = cmd->base.eth_tp_mdix_ctrl;
 
 	/* Restart the PHY */
-	_phy_start_aneg(phydev);
+	if (phy_is_started(phydev)) {
+		phydev->state = PHY_UP;
+		phy_trigger_machine(phydev);
+	} else {
+		_phy_start_aneg(phydev);
+	}
 
 	mutex_unlock(&phydev->lock);
 	return 0;