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Message-ID: <20230809135702.4dencx4ikij7d33y@skbuf>
Date: Wed, 9 Aug 2023 16:58:23 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: Ioana Ciornei <ciorneiioana@...il.com>,
Florian Fainelli <f.fainelli@...il.com>,
"Russell King (Oracle)" <linux@...linux.org.uk>,
Andrew Lunn <andrew@...n.ch>,
Heiner Kallweit <hkallweit1@...il.com>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
Ioana Ciornei <ioana.ciornei@....com>,
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
Hi Uwe,
(I hope the threading won't be broken)
On Fri, Aug 04, 2023 at 09:17:57AM +0200, Uwe Kleine-König wrote:
> Most PHYs signal WoL using an interrupt. So disabling interrupts breaks
> WoL at least on PHYs covered by the marvell driver. So skip disabling
> irqs on shutdown if WoL is enabled.
>
> While at it also explain the motivation that irqs are disabled at all.
>
> Fixes: e2f016cf7751 ("net: phy: add a shutdown procedure")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
> Hello,
>
> while I'm not sure that disabling interrupts is a good idea in general,
> this change at least should fix the WoL case. Note that this change is
> only compile tested as next doesn't boot on my test machine (because of
> https://git.kernel.org/linus/b3574f579ece24439c90e9a179742c61205fbcfa)
> and 6.1 (which is the other kernel I have running) doesn't know about
> .wol_enabled. I don't want to delay this fix until I bisected this new
> issue.
>
> Assuming this patch is eligible for backporting to stable, maybe point
> out that it depends on v6.5-rc1~163^2~286^2~2 ("net: phy: Allow drivers
> to always call into ->suspend()"). Didn't try to backport that.
>
> Best regards
> Uwe
>
> drivers/net/phy/phy_device.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 61921d4dbb13..6d1526bdd1d7 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -3340,6 +3340,15 @@ static void phy_shutdown(struct device *dev)
> if (phydev->state == PHY_READY || !phydev->attached_dev)
> return;
>
> + /* Most phys signal WoL via the irq line. So for these irqs shouldn't be
> + * disabled.
> + */
> + if (phydev->wol_enabled)
> + return;
> +
> + /* On shutdown disable irqs to prevent an irq storm on systems where the
> + * irq line is shared by several devices.
> + */
> phy_disable_interrupts(phydev);
> }
>
> --
> 2.40.1
>
>
I think the idea is not bad and something along these lines might be the
way to go, but I don't think it works (as currently implemented, and
tested by me, prints below).
Upon a quick search, phydev->wol_enabled is only set from phy_suspend(),
and phy_suspend() isn't invoked from the ethnl_set_wol() call stack.
Confirmed this way:
$ ethtool -s end0 wol g # &enet0 in the device tree
$ reboot -f
Rebooting.
[ 288.682444] Qualcomm Atheros AR8031/AR8033 mdio@...4000:02: phy_shutdown: wol_enabled 0
[ 288.690935] Qualcomm Atheros AR8031/AR8033 mdio@...4000:01: phy_shutdown: wol_enabled 0
[ 288.736145] reboot: Restarting system
This is on the arch/arm/boot/dts/nxp/ls/ls1021a-tsn.dts, the same board
as the one which Ioana worked on (with the shared AR8031 PHY interrupts).
Sure, it needs to be mentioned that WoL + shared PHY interrupts is not
by any means an impossible combination, but it still won't work reliably.
I guess that's ok temporarily, since WoL requires user opt-in, so in the
default configuration, the LS1021A-TSN is not broken by this change (in
its functional variant).
pw-bot: cr
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