linux-kernel - Re: [net-next,PATCH] net: stmmac: stm32: Do not suspend downed interface

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Message-ID: <aWfEXX1iMHy3V5sK@shell.armlinux.org.uk>
Date: Wed, 14 Jan 2026 16:29:17 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Marek Vasut <marex@...ladev.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	Christophe Roullier <christophe.roullier@...com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
	kernel@...electronics.com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: Re: [net-next,PATCH] net: stmmac: stm32: Do not suspend downed
 interface

On Wed, Jan 14, 2026 at 09:17:54AM +0100, Marek Vasut wrote:
> If an interface is down, the ETHnSTP clock are not running. Suspending
> such an interface will attempt to stop already stopped ETHnSTP clock,
> and produce a warning in the kernel log about this.
> 
> STM32MP25xx that is booted from NFS root via its first ethernet MAC
> (also the consumer of ck_ker_eth1stp) and with its second ethernet
> MAC downed produces the following warnings during suspend resume
> cycle. This can be provoked even using pm_test:
> 
> "
> $ echo devices > /sys/power/pm_test
> $ echo mem > /sys/power/state
> ...
> ck_ker_eth2stp already disabled
> ...
> ck_ker_eth2stp already unprepared
> ...
> "
> 
> Fix this by not manipulating with the clock during suspend resume
> of interfaces which are downed.

I don't think this is the correct fix. Looking back at my commits:
b51f34bc85e3 net: stmmac: platform: legacy hooks for suspend()/resume() methods
07bbbfe7addf net: stmmac: add suspend()/resume() platform ops

I think I changed the behaviour of the suspend/resume callbacks
unintentionally. Sorry, I don't have time to complete this email
(meeting.)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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