linux-kernel - [PATCH net-next v4 05/10] net: usb: lan78xx: Improve error handling in PHY initialization

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Message-Id: <20250318093410.3047828-6-o.rempel@pengutronix.de>
Date: Tue, 18 Mar 2025 10:34:05 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Woojung Huh <woojung.huh@...rochip.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Russell King <rmk+kernel@...linux.org.uk>,
	Thangaraj Samynathan <Thangaraj.S@...rochip.com>,
	Rengarajan Sundararajan <Rengarajan.S@...rochip.com>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	UNGLinuxDriver@...rochip.com,
	Phil Elwell <phil@...pberrypi.org>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Simon Horman <horms@...nel.org>
Subject: [PATCH net-next v4 05/10] net: usb: lan78xx: Improve error handling in PHY initialization

Ensure that return values from `lan78xx_write_reg()`,
`lan78xx_read_reg()`, and `phy_find_first()` are properly checked and
propagated. Use `ERR_PTR(ret)` for error reporting in
`lan7801_phy_init()` and replace `-EIO` with `-ENODEV` where appropriate
to provide more accurate error codes.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
changes v4:
- split the patch and move part of it before PHYlink migration
---
 drivers/net/usb/lan78xx.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index d2bc6cbdbb66..190c063f8eb9 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -2569,7 +2569,6 @@ static struct phy_device *lan7801_phy_init(struct lan78xx_net *dev)
 {
 	struct phy_device *phydev;
 	int ret;
-	u32 buf;
 
 	phydev = phy_find_first(dev->mdiobus);
 	if (!phydev) {
@@ -2583,28 +2582,27 @@ static struct phy_device *lan7801_phy_init(struct lan78xx_net *dev)
 		if (ret < 0)
 			return ERR_PTR(ret);
 
-		ret = lan78xx_read_reg(dev, HW_CFG, &buf);
-		if (ret < 0)
-			return ERR_PTR(ret);
-
-		buf |= HW_CFG_CLK125_EN_;
-		buf |= HW_CFG_REFCLK25_EN_;
-		ret = lan78xx_write_reg(dev, HW_CFG, buf);
+		ret = lan78xx_update_reg(dev, HW_CFG, HW_CFG_CLK125_EN_ |
+					 HW_CFG_REFCLK25_EN_,
+					 HW_CFG_CLK125_EN_ | HW_CFG_REFCLK25_EN_);
 		if (ret < 0)
 			return ERR_PTR(ret);
 	} else {
 		if (!phydev->drv) {
 			netdev_err(dev->net, "no PHY driver found\n");
-			return NULL;
+			return ERR_PTR(-ENODEV);
 		}
 		phydev->interface = PHY_INTERFACE_MODE_RGMII_ID;
 		/* The PHY driver is responsible to configure proper RGMII
 		 * interface delays. Disable RGMII delays on MAC side.
 		 */
-		lan78xx_write_reg(dev, MAC_RGMII_ID, 0);
+		ret = lan78xx_write_reg(dev, MAC_RGMII_ID, 0);
+		if (ret < 0)
+			return ERR_PTR(ret);
 
 		phydev->is_internal = false;
 	}
+
 	return phydev;
 }
 
@@ -2673,7 +2671,7 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 		phydev = phy_find_first(dev->mdiobus);
 		if (!phydev) {
 			netdev_err(dev->net, "no PHY found\n");
-			return -EIO;
+			return -ENODEV;
 		}
 		phydev->is_internal = true;
 		phydev->interface = PHY_INTERFACE_MODE_GMII;
@@ -2681,7 +2679,7 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 
 	default:
 		netdev_err(dev->net, "Unknown CHIP ID found\n");
-		return -EIO;
+		return -ENODEV;
 	}
 
 	/* if phyirq is not set, use polling mode in phylib */
@@ -2695,7 +2693,7 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 	if (ret) {
 		netdev_err(dev->net, "can't attach PHY to %s, error %pe\n",
 			   dev->mdiobus->id, ERR_PTR(ret));
-		return -EIO;
+		return ret;
 	}
 
 	phy_support_eee(phydev);
-- 
2.39.5