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Message-Id: <20170915.142622.1357636170906048191.davem@davemloft.net>
Date: Fri, 15 Sep 2017 14:26:22 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: geert+renesas@...der.be
Cc: steve.glendinning@...well.net, andrew@...n.ch,
f.fainelli@...il.com, netdev@...r.kernel.org,
linux-pm@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: smsc911x: Quieten netif during suspend
From: Geert Uytterhoeven <geert+renesas@...der.be>
Date: Wed, 13 Sep 2017 19:42:05 +0200
> If the network interface is kept running during suspend, the net core
> may call net_device_ops.ndo_start_xmit() while the Ethernet device is
> still suspended, which may lead to a system crash.
>
> E.g. on sh73a0/kzm9g and r8a73a4/ape6evm, the external Ethernet chip is
> driven by a PM controlled clock. If the Ethernet registers are accessed
> while the clock is not running, the system will crash with an imprecise
> external abort.
>
> As this is a race condition with a small time window, it is not so easy
> to trigger at will. Using pm_test may increase your chances:
>
> # echo 0 > /sys/module/printk/parameters/console_suspend
> # echo platform > /sys/power/pm_test
> # echo mem > /sys/power/state
>
> To fix this, make sure the network interface is quietened during
> suspend.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
Applied.
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