Re: [PATCH net-next v2 2/4] net: stmmac: stm32: add WoL from PHY support

[Florian Fainelli <florian.fainelli@broadcom.com>]

On 9/26/2025 12:05 PM, Florian Fainelli wrote:
> 
> 
> On 9/26/2025 10:59 AM, Russell King (Oracle) wrote:
>> On Wed, Sep 17, 2025 at 05:31:16PM +0100, Russell King (Oracle) wrote:
>>> On Wed, Sep 17, 2025 at 05:36:37PM +0200, Gatien Chevallier wrote:
>>>> If the "st,phy-wol" property is present in the device tree node,
>>>> set the STMMAC_FLAG_USE_PHY_WOL flag to use the WoL capability of
>>>> the PHY.
>>>>
>>>> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
>>>> ---
>>>>   drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c | 5 +++++
>>>>   1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c b/ 
>>>> drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>>>> index 
>>>> 77a04c4579c9dbae886a0b387f69610a932b7b9e..6f197789cc2e8018d6959158b795e4bca46869c5 100644
>>>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
>>>> @@ -106,6 +106,7 @@ struct stm32_dwmac {
>>>>       u32 speed;
>>>>       const struct stm32_ops *ops;
>>>>       struct device *dev;
>>>> +    bool phy_wol;
>>>>   };
>>>>   struct stm32_ops {
>>>> @@ -433,6 +434,8 @@ static int stm32_dwmac_parse_data(struct 
>>>> stm32_dwmac *dwmac,
>>>>           }
>>>>       }
>>>> +    dwmac->phy_wol = of_property_read_bool(np, "st,phy-wol");
>>>> +
>>>>       return err;
>>>>   }
>>>> @@ -557,6 +560,8 @@ static int stm32_dwmac_probe(struct 
>>>> platform_device *pdev)
>>>>       plat_dat->bsp_priv = dwmac;
>>>>       plat_dat->suspend = stm32_dwmac_suspend;
>>>>       plat_dat->resume = stm32_dwmac_resume;
>>>> +    if (dwmac->phy_wol)
>>>> +        plat_dat->flags |= STMMAC_FLAG_USE_PHY_WOL;
>>>
>>> I would much rather we found a different approach, rather than adding
>>> custom per-driver DT properties to figure this out.
>>>
>>> Andrew has previously suggested that MAC drivers should ask the PHY
>>> whether WoL is supported, but this pre-supposes that PHY drivers are
>>> coded correctly to only report WoL capabilities if they are really
>>> capable of waking the system. As shown in your smsc PHY driver patch,
>>> this may not be the case.
>>>
>>> Given that we have historically had PHY drivers reporting WoL
>>> capabilities without being able to wake the system, we can't
>>> implement Andrew's suggestion easily.
>>>
>>> The only approach I can think that would allow us to transition is
>>> to add:
>>>
>>> static inline bool phy_can_wakeup(struct phy_device *phy_dev)
>>> {
>>>     return device_can_wakeup(&phy_dev->mdio.dev);
>>> }
>>>
>>> to include/linux/phy.h, and a corresponding wrapper for phylink.
>>> This can then be used to determine whether to attempt to use PHY-based
>>> Wol in stmmac_get_wol() and rtl8211f_set_wol(), falling back to
>>> PMT-based WoL if supported at the MAC.
>>>
>>> So, maybe something like:
>>>
>>> static u32 stmmac_wol_support(struct stmmac_priv *priv)
>>> {
>>>     u32 support = 0;
>>>
>>>     if (priv->plat->pmt && device_can_wakeup(priv->device)) {
>>>         support = WAKE_UCAST;
>>>         if (priv->hw_cap_support && priv->dma_cap.pmt_magic_frame)
>>>             support |= WAKE_MAGIC;
>>>     }
>>>
>>>     return support;
>>> }
>>>
>>> static void stmmac_get_wol(struct net_device *dev, struct 
>>> ethtool_wolinfo *wol)
>>> {
>>>     struct stmmac_priv *priv = netdev_priv(dev);
>>>     int err;
>>>
>>>     /* Check STMMAC_FLAG_USE_PHY_WOL for legacy */
>>>     if (phylink_can_wakeup(priv->phylink) ||
>>>         priv->plat->flags & STMMAC_FLAG_USE_PHY_WOL) {
>>>         err = phylink_ethtool_get_wol(priv->phylink, wol);
>>>         if (err != 0 && err != -EOPNOTSUPP)
>>>             return;
>>>     }
>>>
>>>     wol->supported |= stmmac_wol_support(priv);
>>>
>>>     /* A read of priv->wolopts is single-copy atomic. Locking
>>>      * doesn't add any benefit.
>>>      */
>>>     wol->wolopts |= priv->wolopts;
>>> }
>>>
>>> static int stmmac_set_wol(struct net_device *dev, struct 
>>> ethtool_wolinfo *wol)
>>> {
>>>     struct stmmac_priv *priv = netdev_priv(dev);
>>>     u32 support, wolopts;
>>>     int err;
>>>
>>>     wolopts = wol->wolopts;
>>>
>>>     /* Check STMMAC_FLAG_USE_PHY_WOL for legacy */
>>>     if (phylink_can_wakeup(priv->phylink) ||
>>>         priv->plat->flags & STMMAC_FLAG_USE_PHY_WOL) {
>>>         struct ethtool_wolinfo w;
>>>
>>>         err = phylink_ethtool_set_wol(priv->phylink, wol);
>>>         if (err != -EOPNOTSUPP)
>>>             return err;
>>>
>>>         /* Remove the WoL modes that the PHY is handling */
>>>         if (!phylink_ethtool_get_wol(priv->phylink, &w))
>>>             wolopts &= ~w.wolopts;
>>>     }
>>>
>>>     support = stmmac_wol_support(priv);
>>>
>>>     mutex_lock(&priv->lock);
>>>     priv->wolopts = wolopts & support;
>>>     device_set_wakeup_enable(priv->device, !!priv->wolopts);
>>>     mutex_unlock(&priv->lock);
>>>
>>>     return 0;
>>> }
>>>
>>> ... and now I'm wondering whether this complexity is something that
>>> phylink should handle internally, presenting a mac_set_wol() method
>>> to configure the MAC-side WoL settings. What makes it difficult to
>>> just move into phylink is the STMMAC_FLAG_USE_PHY_WOL flag, but
>>> that could be a "force_phy_wol" flag in struct phylink_config as
>>> a transitionary measure... so long as PHY drivers get fixed.
>>
>> I came up with this as an experiment - I haven't tested it beyond
>> running it through the compiler (didn't let it get to the link stage
>> yet.) Haven't even done anything with it for stmmac yet.
>>
> 
> I like the direction this is going, we could probably take one step 
> further and extract the logic present in bcmgenet_wol.c and make those 
> helper functions for other drivers to get the overlay of PHY+MAC WoL 
> options/password consistent across all drivers. What do you think?

+		if (wolopts & WAKE_MAGIC)
+			changed |= !!memcmp(wol->sopass, pl->wol_sopass,
+					    sizeof(wol->sopass));


Should not the hunk above be wolopts & WAKE_MAGICSECURE?

-- 
Florian