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

From: Rengarajan.S
Date: Tue Mar 25 2025 - 13:47:15 EST

Hi Oleksij,

On Wed, 2025-03-19 at 09:49 +0100, Oleksij Rempel wrote:
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>
> 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);
> +

I noticed that fixed_phy_register is removed in later patches. However,
in the above implementation, if a failure occurs we exit without
unregistering it. To avoid this issue, can we include the patch that
removes fixed_phy_register first to avoid the cleanup scenario?

> 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
>