netdev - Re: [PATCH net] net: phy: fix IRQ-based wake-on-lan over hibernate / power off

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Date: Fri, 11 Aug 2023 11:30:50 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
 Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>
Cc: 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>,
 "David S. Miller" <davem@...emloft.net>,
 Divya Koppera <Divya.Koppera@...rochip.com>,
 Eric Dumazet <edumazet@...gle.com>, Hauke Mehrtens <hauke@...ke-m.de>,
 Ioana Ciornei <ioana.ciornei@....com>, Jakub Kicinski <kuba@...nel.org>,
 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>, Paolo Abeni <pabeni@...hat.com>,
 Philippe Schenker <philippe.schenker@...adex.com>,
 Willy Liu <willy.liu@...ltek.com>, Yuiko Oshino
 <yuiko.oshino@...rochip.com>,
 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 netdev@...r.kernel.org
Subject: Re: [PATCH net] net: phy: fix IRQ-based wake-on-lan over hibernate /
 power off

On 8/11/23 03:26, Russell King (Oracle) wrote:
> Uwe reports:
> "Most PHYs signal WoL using an interrupt. So disabling interrupts [at
> shutdown] breaks WoL at least on PHYs covered by the marvell driver."
> 
> Discussing with Ioana, the problem which was trying to be solved was:
> "The board in question is a LS1021ATSN which has two AR8031 PHYs that
> share an interrupt line. In case only one of the PHYs is probed and
> there are pending interrupts on the PHY#2 an IRQ storm will happen
> since there is no entity to clear the interrupt from PHY#2's registers.
> PHY#1's driver will get stuck in .handle_interrupt() indefinitely."
> 
> Further confirmation that "the two AR8031 PHYs are on the same MDIO
> bus."
> 
> With WoL using interrupts to wake the system, in such a case, the
> system will begin booting with an asserted interrupt. Thus, we need to
> cope with an interrupt asserted during boot.
> 
> Solve this instead by disabling interrupts during PHY probe. This will
> ensure in Ioana's situation that both PHYs of the same type sharing an
> interrupt line on a common MDIO bus will have their interrupt outputs
> disabled when the driver probes the device, but before we hook in any
> interrupt handlers - thus avoiding the interrupt storm.
> 
> A better fix would be for platform firmware to disable the interrupting
> devices at source during boot, before control is handed to the kernel.
> 
> Fixes: e2f016cf7751 ("net: phy: add a shutdown procedure")
> Link: 20230804071757.383971-1-u.kleine-koenig@...gutronix.de
> Reported-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
-- 
Florian