Re: [PATCH] net: phy: Don't disable irqs on shutdown if WoL is enabled

[Florian Fainelli <f.fainelli@gmail.com>]

On 8/9/2023 9:21 AM, Andrew Lunn wrote:
>> Thinking about this, I wonder whether we could solve your issue by
>> disabling interrupts when the PHY is probed, rather than disabling
>> them on shutdown - something like this? (not build tested)
>>
>> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
>> index 3e9909b30938..4d1a37487923 100644
>> --- a/drivers/net/phy/phy_device.c
>> +++ b/drivers/net/phy/phy_device.c
>> @@ -3216,6 +3216,8 @@ static int phy_probe(struct device *dev)
>>   			goto out;
>>   	}
>>   
>> +        phy_disable_interrupts(phydev);
>> +
>>   	/* Start out supporting everything. Eventually,
>>   	 * a controller will attach, and may modify one
>>   	 * or both of these values
> 
> At some point, the interrupt is going to be enabled again. And then
> the WoL interrupt will fire. I think some PHY drivers actually need to
> see that WoL interrupt. e.g. the marvell driver has this comment:
> 
> static int m88e1318_set_wol(struct phy_device *phydev,
>                              struct ethtool_wolinfo *wol)
> {
> ....
>                  /* If WOL event happened once, the LED[2] interrupt pin
>                   * will not be cleared unless we reading the interrupt status
>                   * register. If interrupts are in use, the normal interrupt
>                   * handling will clear the WOL event. Clear the WOL event
>                   * before enabling it if !phy_interrupt_is_valid()
>                   */
> 
> So it seems like just probing the marvell PHY is not enough to clear
> the WoL interrupt.
> 
> Can we be sure that the other PHY has reached a state it can handle
> and clear an interrupt when we come to enable the interrupt? I think
> not, especially in cases like NFS root, where the interface will be
> put into use as soon as it exists, maybe before the other interface
> has probed.

Does it really make sense to have the PHY be interrupt driven for this 
specific board configuration if this causes so much hassle?
-- 
Florian