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

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Date: Wed, 9 Aug 2023 10:04:31 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Andrew Lunn <andrew@...n.ch>,
 "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Ioana Ciornei <ioana.ciornei@....com>, Jakub Kicinski <kuba@...nel.org>,
 Heiner Kallweit <hkallweit1@...il.com>,
 Uwe Kleine-K├Ânig <u.kleine-koenig@...gutronix.de>,
 Ioana Ciornei <ciorneiioana@...il.com>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 Alexandru Ardelean <alexandru.ardelean@...log.com>,
 Andre Edich <andre.edich@...rochip.com>, Antoine Tenart
 <atenart@...nel.org>, Baruch Siach <baruch@...s.co.il>,
 Christophe Leroy <christophe.leroy@....fr>,
 Divya Koppera <Divya.Koppera@...rochip.com>,
 Hauke Mehrtens <hauke@...ke-m.de>, Jerome Brunet <jbrunet@...libre.com>,
 Kavya Sree Kotagiri <kavyasree.kotagiri@...rochip.com>,
 Linus Walleij <linus.walleij@...aro.org>,
 Marco Felsch <m.felsch@...gutronix.de>, Marek Vasut <marex@...x.de>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 Mathias Kresin <dev@...sin.me>, Maxim Kochetkov <fido_max@...ox.ru>,
 Michael Walle <michael@...le.cc>, Neil Armstrong <narmstrong@...libre.com>,
 Nisar Sayed <Nisar.Sayed@...rochip.com>,
 Oleksij Rempel <o.rempel@...gutronix.de>,
 Philippe Schenker <philippe.schenker@...adex.com>,
 Willy Liu <willy.liu@...ltek.com>, Yuiko Oshino <yuiko.oshino@...rochip.com>
Subject: Re: [PATCH] net: phy: Don't disable irqs on shutdown if WoL is
 enabled



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