Re: [PATCH net-next v3 5/7] usbnet: smsc95xx: Forward PHY interrupts to PHY driver to avoid polling

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 24.05.2022 03:08, Andrew Lunn wrote:
>> @@ -976,6 +977,25 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
>>   	struct phy_driver *drv = phydev->drv;
>>   	irqreturn_t ret;
>>   
>> +	if (IS_ENABLED(CONFIG_PM_SLEEP) &&
>> +	    (phydev->mdio.dev.power.is_prepared ||
>> +	     phydev->mdio.dev.power.is_suspended)) {
>> +		struct net_device *netdev = phydev->attached_dev;
>> +
>> +		if (netdev) {
>> +			struct device *parent = netdev->dev.parent;
>> +
>> +			if (netdev->wol_enabled)
>> +				pm_system_wakeup();
>> +			else if (device_may_wakeup(&netdev->dev))
>> +				pm_wakeup_dev_event(&netdev->dev, 0, true);
>> +			else if (parent && device_may_wakeup(parent))
>> +				pm_wakeup_dev_event(parent, 0, true);
>> +		}
>> +
>> +		return IRQ_HANDLED;
> I'm not sure you can just throw the interrupt away. There have been
> issues with WoL, where the WoL signal has been applied to a PMC, not
> an actual interrupt. Yet the PHY driver assumes it is an
> interrupt. And in order for WoL to work correctly, it needs the
> interrupt handler to be called. We said the hardware is broken, WoL
> cannot work for that setup.
>
> Here you have correct hardware, but you are throwing the interrupt
> away, which will have the same result. So i think you need to abort
> the suspend, get the bus working again, and call the interrupt
> handler. If this is a WoL interrupt you are supposed to be waking up
> anyway.

This hardware doesn't support wake-on-lan. It looks somehow that it 
manages to throw an interrupt just a moment before the power regulator 
for the whole usb bus is cut off.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland