From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Nicolai Buchwitz <nb@tipi-net.de>
Cc: netdev@vger.kernel.org, Phil Elwell <phil@raspberrypi.com>,
Andrew Lunn <andrew@lunn.ch>,
Heiner Kallweit <hkallweit1@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] net: phy: microchip: enable downshift by default on LAN88xx
Date: Tue, 31 Mar 2026 12:32:14 +0100 [thread overview]
Message-ID: <acuwvoydmJusuj9x@shell.armlinux.org.uk> (raw)
In-Reply-To: <20260330224630.579937-3-nb@tipi-net.de>
On Tue, Mar 31, 2026 at 12:46:27AM +0200, Nicolai Buchwitz wrote:
> Enable auto-downshift from 1000BASE-T to 100BASE-TX after 2 failed
> auto-negotiation attempts by default. This ensures that links with
> faulty or missing cable pairs (C and D) fall back to 100Mbps without
> requiring userspace configuration.
>
> Users can override or disable downshift at runtime:
>
> ethtool --set-phy-tunable eth0 downshift off
>
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
I'm slightly concerned by this commit. ->config_init() is called when
the netdev attaches the PHY, and also during the resume path - and it's
the second one which I believe is a problem here.
If the user has configured the downshift, it is reasonable for the user
to expect the setting to be preserved over a suspend/resume. However,
by placing this code in ->config_init(), you will overwrite the user's
setting when the system resumes.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2026-03-31 11:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-30 22:46 [PATCH net-next v2 0/2] net: phy: microchip: add downshift support for LAN88xx Nicolai Buchwitz
2026-03-30 22:46 ` [PATCH v2 1/2] net: phy: microchip: add downshift tunable " Nicolai Buchwitz
2026-03-31 1:02 ` Andrew Lunn
2026-03-31 11:29 ` Russell King (Oracle)
2026-03-31 11:40 ` Nicolai Buchwitz
2026-03-30 22:46 ` [PATCH v2 2/2] net: phy: microchip: enable downshift by default on LAN88xx Nicolai Buchwitz
2026-03-31 11:32 ` Russell King (Oracle) [this message]
2026-03-31 11:58 ` Nicolai Buchwitz
2026-03-31 12:01 ` Russell King (Oracle)
2026-03-31 12:41 ` Nicolai Buchwitz
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