[PATCH RFC net-next 2/6] net: phy: add phy_may_wakeup()

[Russell King (Oracle)]

On Tue, Sep 30, 2025 at 11:04:28AM +0200, Gatien CHEVALLIER wrote:
> Hi Russell,
> 
> First of all, thank you for taking the time to propose something.
> 
> IIUC, using ethtool to enable WoL with, e.g: "ethtool -s end0 wol g"
> even if the WoL isn't really supported will prevent the phy suspend.

This is correct - whenever a PHY has WoL enabled, it won't be suspended
as it has to listen for the configured wake-up packet(s).

> Therefore, PHY drivers should be adapted to implement something like:
> 
> 	if (!device_can_wakeup(&dev->mdio.dev))
> 		return -EOPNOTSUPP;
> 
> in their set_wol() ops to fully adapt to what you propose, right?

That's not sufficient. Yes, it's one of the things they need to do.

1. get_wol() should set ->supported to 0 (or at least not add anything
   to it) if wake-up is not possible.

2. set_wol() should not enable WoL modes or return -EOPNOTSUPP as you
   have above if wake-up is not possible. It should also call
   device_set_wakeup_enable() to indicate whether wake-up has been
   enabled for this device or not.

3. the PHY driver's probe function needs to be modified to call 
   device_set_wakeup_capable() to configure whether this device _really_
   can wake-up the system. See realtek_main.c::rtl8211f_probe() and
   broadcom.c as examples.

4. if using interrupt-based wake-up, use devm_pm_set_wake_irq() so
   the driver core can manage the irq-wake configuration.

See realtek_main.c - that's the driver I recently fixed (it had many
issues).

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