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.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!