Subject: Re: [PATCH net-next 2/2] net: phy: Introduce Airoha AN8801/R Gigabit Ethernet PHY driver

From: "Russell King (Oracle)" <[email-masked]>
Date: Wed, 4 Mar 2026 16:32:10 +0000

On Wed, Mar 04, 2026 at 10:35:29AM +0100, Louis-Alexis Eyraud wrote:
> +static void an8801r_get_wol(struct phy_device *phydev,
> +			    struct ethtool_wolinfo *wol)
> +{
> +	u32 reg_val;
> +
> +	air_buckpbus_reg_read(phydev, AN8801_BPBUS_REG_WAKEUP_CTL1, &reg_val);
> +
> +	wol->supported = WAKE_MAGIC;
> +
> +	if (reg_val & AN8801_WOL_WAKE_MAGIC_EN)
> +		wol->wolopts |= WAKE_MAGIC;
> +	else
> +		wol->wolopts &= ~WAKE_MAGIC;

Please only support WoL if you know that the PHY has been wired up in
such a way to allow it to actually wake the system. The PHY itself
merely supporting WoL is insufficient.

Please look at my recent change to realtek_main.c in commit
b826bf795564 ("net: phy: realtek: fix RTL8211F wake-on-lan support")
to see a possible way to achieve this.

> +static int an8801r_config_init(struct phy_device *phydev)
> +{
> +	u8 led_default_function[AN8801R_NUM_LEDS] = { 0 };
> +	int prev_page, ret;
> +
> +	ret = an8801r_of_init_leds(phydev, led_default_function);
> +	if (ret)
> +		return ret;
> +
> +	/* Disable Low Power Mode (LPM) */
> +	ret = phy_write_mmd(phydev, MDIO_MMD_VEND2, AN8801_REG_PHY_INTERNAL0,
> +			    FIELD_PREP(AN8801_PHY_INTFUNC_MASK, 0x1e));
> +	if (ret)
> +		return ret;
> +
> +	ret = phy_write_mmd(phydev, MDIO_MMD_VEND2, AN8801_REG_PHY_INTERNAL1,
> +			    FIELD_PREP(AN8801_PHY_INTFUNC_MASK, 0x2));
> +	if (ret)
> +		return ret;
> +
> +	/* Disable EEE by default */
> +	ret = phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, 0);
> +	if (ret)
> +		return ret;

Are you sure this is safe, e.g. over a suspend/resume, and doesn't
cause the hardware vs software state to desync?

> +
> +	prev_page = phy_select_page(phydev, AIR_PHY_PAGE_EXTENDED_1);
> +	if (prev_page < 0)
> +		return prev_page;

No, this is buggy. Please read the phy_select_page() documentation to
find out why.

> +
> +	/* Set the PHY to perform auto-downshift after 3 auto-negotiation
> +	 * attempts
> +	 */
> +	__phy_write(phydev, AN8801_EXT_REG_PHY,
> +		    FIELD_PREP(AN8801_EXT_PHY_CTRL1, 0x1d) |
> +		    FIELD_PREP(AN8801_EXT_PHY_DOWNSHIFT_CTL, 1) |
> +		    AN8801_EXT_PHY_DOWNSHIFT_EN);
> +
> +	ret = phy_restore_page(phydev, prev_page, ret);
> +	if (ret)
> +		return ret;

However, the bug could've been avoided by using the appropriate
accessor:

	ret = phy_write_paged(phydev, AIR_PHY_PAGE_EXTENDED_1,
			      AN8801_EXT_REG_PHY,
			      FIELD_PREP(AN8801_EXT_PHY_CTRL1, 0x1d) |
			      FIELD_PREP(AN8801_EXT_PHY_DOWNSHIFT_CTL, 1) |
			      AN8801_EXT_PHY_DOWNSHIFT_EN);
	if (ret < 0)
		return ret;

> +static int an8801r_read_status(struct phy_device *phydev)
> +{
> +	int prev_speed, ret;
> +	u32 val;
> +
> +	prev_speed = phydev->speed;
> +
> +	ret = genphy_read_status(phydev);
> +	if (ret)
> +		return ret;
> +
> +	if (!phydev->link)
> +		return 0;
> +
> +	if (prev_speed != phydev->speed) {

Maybe:

	if (phydev->link && prev_speed != phydev->speed) {

?

Thanks.

-- 
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