linux-kernel - Re: [PATCH RFC net-next 0/3] net: dsa: initial support for MaxLinear MxL862xx switches

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Message-ID: <aTGVNfF618wssihg@shell.armlinux.org.uk>
Date: Thu, 4 Dec 2025 14:05:41 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Daniel Golle <daniel@...rotopia.org>
Cc: Vladimir Oltean <olteanv@...il.com>, Andrew Lunn <andrew@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Simon Horman <horms@...nel.org>,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, Frank Wunderlich <frankwu@....de>,
	Avinash Jayaraman <ajayaraman@...linear.com>,
	Bing tao Xu <bxu@...linear.com>, Liang Xu <lxu@...linear.com>,
	Juraj Povazanec <jpovazanec@...linear.com>,
	"Fanni (Fang-Yi) Chan" <fchan@...linear.com>,
	"Benny (Ying-Tsan) Weng" <yweng@...linear.com>,
	"Livia M. Rosu" <lrosu@...linear.com>,
	John Crispin <john@...ozen.org>
Subject: Re: [PATCH RFC net-next 0/3] net: dsa: initial support for MaxLinear
 MxL862xx switches

On Thu, Dec 04, 2025 at 01:08:24PM +0000, Daniel Golle wrote:
> On Thu, Dec 04, 2025 at 01:02:14AM +0000, Russell King (Oracle) wrote:
> > On Wed, Dec 03, 2025 at 11:23:11PM +0000, Daniel Golle wrote:
> > > On Wed, Dec 03, 2025 at 10:26:05PM +0200, Vladimir Oltean wrote:
> > > > Hi Daniel,
> > > > 
> > > > On Tue, Dec 02, 2025 at 11:37:13PM +0000, Daniel Golle wrote:
> > > > > Hi,
> > > > > 
> > > > > This series adds very basic DSA support for the MaxLinear MxL86252
> > > > > (5 PHY ports) and MxL86282 (8 PHY ports) switches. The intent is to
> > > > > validate and get feedback on the overall approach and driver structure,
> > > > > especially the firmware-mediated host interface.
> > > > > 
> > > > > MxL862xx integrates a firmware running on an embedded processor (Zephyr
> > > > > RTOS). Host interaction uses a simple API transported over MDIO/MMD.
> > > > > This series includes only what's needed to pass traffic between user
> > > > > ports and the CPU port: relayed MDIO to internal PHYs, basic port
> > > > > enable/disable, and CPU-port special tagging.
> > > > > 
> > > > > Thanks for taking a look.
> > > > 
> > > > I see no phylink_mac_ops in your patches.
> > > 
> > 
> > As you didn't respond to Vladimir's statement here, I will also echo
> > this. Why do you have no phylink_mac_ops ?
> > 
> > New DSA drivers are expected to always have phylink_mac_ops, and not
> > rely on the legacy fallback in net/dsa/port.c
> 
> All three phylink_mac_ops functions are no-ops for the internal PHYs,
> see also
> 
> https://github.com/frank-w/BPI-Router-Linux/blob/6.18-rc/drivers/net/dsa/mxl862xx/mxl862xx.c#L3242

While you may end up with the same three methods remaining empty,
please do not rely on the legacy fallback, even temporarily.

Thanks.

-- 
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