netdev - [PATCH net v2 2/2] smsc911x: avoid PHY being resumed when interface is not up

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Date:   Mon, 20 Mar 2023 10:20:41 +0100
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     netdev@...r.kernel.org
Cc:     linux-renesas-soc@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Steve Glendinning <steve.glendinning@...well.net>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net v2 2/2] smsc911x: avoid PHY being resumed when interface is not up

SMSC911x doesn't need mdiobus suspend/resume, that's why it sets
'mac_managed_pm'. However, setting it needs to be moved from init to
probe, so mdiobus PM functions will really never be called (e.g. when
the interface is not up yet during suspend/resume). The errno is changed
because ENODEV has a special meaning when returned in probe().

Fixes: 3ce9f2bef755 ("net: smsc911x: Stop and start PHY during suspend and resume")
Suggested-by: Heiner Kallweit <hkallweit1@...il.com>
Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
---
Changes since v1:
* no change

In smsc911x_mii_probe(), I remove the sanity check for 'phydev' because
it was already done in smsc911x_mii_init(). Let me know if this is
acceptable or if a more defensive approach is favoured.


 drivers/net/ethernet/smsc/smsc911x.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index 67cb5eb9c716..8b875bbbc05e 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -1019,12 +1019,7 @@ static int smsc911x_mii_probe(struct net_device *dev)
 	struct phy_device *phydev = NULL;
 	int ret;
 
-	/* find the first phy */
 	phydev = phy_find_first(pdata->mii_bus);
-	if (!phydev) {
-		netdev_err(dev, "no PHY found\n");
-		return -ENODEV;
-	}
 
 	SMSC_TRACE(pdata, probe, "PHY: addr %d, phy_id 0x%08X",
 		   phydev->mdio.addr, phydev->phy_id);
@@ -1037,8 +1032,6 @@ static int smsc911x_mii_probe(struct net_device *dev)
 		return ret;
 	}
 
-	/* Indicate that the MAC is responsible for managing PHY PM */
-	phydev->mac_managed_pm = true;
 	phy_attached_info(phydev);
 
 	phy_set_max_speed(phydev, SPEED_100);
@@ -1066,6 +1059,7 @@ static int smsc911x_mii_init(struct platform_device *pdev,
 			     struct net_device *dev)
 {
 	struct smsc911x_data *pdata = netdev_priv(dev);
+	struct phy_device *phydev;
 	int err = -ENXIO;
 
 	pdata->mii_bus = mdiobus_alloc();
@@ -1108,6 +1102,15 @@ static int smsc911x_mii_init(struct platform_device *pdev,
 		goto err_out_free_bus_2;
 	}
 
+	phydev = phy_find_first(pdata->mii_bus);
+	if (!phydev) {
+		netdev_err(dev, "no PHY found\n");
+		err = -ENOENT;
+		goto err_out_free_bus_2;
+	}
+
+	phydev->mac_managed_pm = true;
+
 	return 0;
 
 err_out_free_bus_2:
-- 
2.30.2