[PATCH net-next v5 1/6] net: usb: lan78xx: Improve error handling in PHY initialization

[Oleksij Rempel]

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@xxxxxxxxxxxxxx>
---
changes v5:
- make sure lan7801_phy_init() caller is testing against IS_ERR
  instead of NULL.
changes v4:
- split the patch and move part of it before PHYlink migration
---
 drivers/net/usb/lan78xx.c | 47 ++++++++++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 137adf6d5b08..13b5da18850a 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -2510,14 +2510,13 @@ static void lan78xx_remove_irq_domain(struct lan78xx_net *dev)
 
 static struct phy_device *lan7801_phy_init(struct lan78xx_net *dev)
 {
-	u32 buf;
-	int ret;
 	struct fixed_phy_status fphy_status = {
 		.link = 1,
 		.speed = SPEED_1000,
 		.duplex = DUPLEX_FULL,
 	};
 	struct phy_device *phydev;
+	int ret;
 
 	phydev = phy_find_first(dev->mdiobus);
 	if (!phydev) {
@@ -2525,30 +2524,40 @@ static struct phy_device *lan7801_phy_init(struct lan78xx_net *dev)
 		phydev = fixed_phy_register(PHY_POLL, &fphy_status, NULL);
 		if (IS_ERR(phydev)) {
 			netdev_err(dev->net, "No PHY/fixed_PHY found\n");
-			return NULL;
+			return ERR_PTR(-ENODEV);
 		}
 		netdev_dbg(dev->net, "Registered FIXED PHY\n");
 		dev->interface = PHY_INTERFACE_MODE_RGMII;
 		ret = lan78xx_write_reg(dev, MAC_RGMII_ID,
 					MAC_RGMII_ID_TXC_DELAY_EN_);
+		if (ret < 0)
+			return ERR_PTR(ret);
+
 		ret = lan78xx_write_reg(dev, RGMII_TX_BYP_DLL, 0x3D00);
-		ret = lan78xx_read_reg(dev, HW_CFG, &buf);
-		buf |= HW_CFG_CLK125_EN_;
-		buf |= HW_CFG_REFCLK25_EN_;
-		ret = lan78xx_write_reg(dev, HW_CFG, buf);
+		if (ret < 0)
+			return ERR_PTR(ret);
+
+		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(-EINVAL);
 		}
 		dev->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;
 }
 
@@ -2562,9 +2571,10 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 	switch (dev->chipid) {
 	case ID_REV_CHIP_ID_7801_:
 		phydev = lan7801_phy_init(dev);
-		if (!phydev) {
-			netdev_err(dev->net, "lan7801: PHY Init Failed");
-			return -EIO;
+		if (IS_ERR(phydev)) {
+			netdev_err(dev->net, "lan7801: failed to init PHY: %pe\n",
+				   phydev);
+			return PTR_ERR(phydev);
 		}
 		break;
 
@@ -2573,7 +2583,7 @@ 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;
 		dev->interface = PHY_INTERFACE_MODE_GMII;
@@ -2581,7 +2591,7 @@ 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 */
@@ -2633,7 +2643,10 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 						      sizeof(u32));
 		if (len >= 0) {
 			/* Ensure the appropriate LEDs are enabled */
-			lan78xx_read_reg(dev, HW_CFG, &reg);
+			ret = lan78xx_read_reg(dev, HW_CFG, &reg);
+			if (ret < 0)
+				return ret;
+
 			reg &= ~(HW_CFG_LED0_EN_ |
 				 HW_CFG_LED1_EN_ |
 				 HW_CFG_LED2_EN_ |
@@ -2642,7 +2655,9 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
 				(len > 1) * HW_CFG_LED1_EN_ |
 				(len > 2) * HW_CFG_LED2_EN_ |
 				(len > 3) * HW_CFG_LED3_EN_;
-			lan78xx_write_reg(dev, HW_CFG, reg);
+			ret = lan78xx_write_reg(dev, HW_CFG, reg);
+			if (ret < 0)
+				return ret;
 		}
 	}
 
-- 
2.39.5