From nobody Mon Dec 1 22:03:17 2025 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7424C3009F8; Thu, 27 Nov 2025 17:19:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764263951; cv=none; b=L+R8KSryJPmiaOE3ixOhvPE00jW9ow+HhYOA7hSj2izmV8rkHhBIRRVoxIKX2V1yGHpPqpUTMR604Mx/3nVpeljhPCxT6Qw9keJn+J8+er55Djm6z8tiJLmccM7vGvKvzFlZ5aYAZbkzhuycxDjPCD2rvdsUu/TkxDxwE5MNJ9A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764263951; c=relaxed/simple; bh=fdnEnqUIvRRQ7OoetlTpHuupVJmK5WuJbvkJuDwjR5Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kT+l6uA6RRHRJnZQt+5VAtCbNp6NfuKbuDZqNlizcDHV0uhbH5p9A4YkDrMB0vByd3UXUFfy1VMUqs+wrH9zR+4NJoTshUOWvsJCrRV6sIrVb8/iSEX4ELZiaIAb2QEYO+PLNQ+5Cg2LA4D03zQa3AqqfXT+lJLX5GQzsoD7QtU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=qDJx/e3r; arc=none smtp.client-ip=185.246.85.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="qDJx/e3r" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id CDF394E41926; Thu, 27 Nov 2025 17:19:07 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id A162460722; Thu, 27 Nov 2025 17:19:07 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 0BCCF103C8C5F; Thu, 27 Nov 2025 18:19:02 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1764263946; h=from:subject:date:message-id:to:cc:mime-version: content-transfer-encoding:in-reply-to:references; bh=U0kyUILWemPPg53yd8Kio777Xm2al4J0axsqNddordE=; b=qDJx/e3r/tGrgNs5jIoloYImgzeR5c4Ezg1PEj/SkNMu5+EWAy6CbcfhDt2ohS3f0vueil wIGwVCMYs4sUtwSiS4qzyYM4MStbEi5Y+WA2t+ch6EgGbQSrgKma7Mw5Q6OOjdZFSIWFqM PqPNiaasRL+aSG1eOrr9Unzfy5D5+DbUEYI/6a3d0XKYUP3oqW/t0OmR1wKfa37qIpuk+x 4Y9Pg3Hwh2qZD4gJHvjHn20w8KSFbE1/PSMp1VdJVk36EJrcYn0Qn9BsBuDEUuMxDyTuSR kgmov8/1t2RQziStM0sJgbC2Qm/9+KY6tfPST6N8a9c6clf0QmFHvEPMsqTvFA== From: Maxime Chevallier To: davem@davemloft.net Cc: Maxime Chevallier , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, thomas.petazzoni@bootlin.com, Andrew Lunn , Jakub Kicinski , Eric Dumazet , Paolo Abeni , Russell King , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Herve Codina , Florian Fainelli , Heiner Kallweit , Vladimir Oltean , =?UTF-8?q?K=C3=B6ry=20Maincent?= , =?UTF-8?q?Marek=20Beh=C3=BAn?= , Oleksij Rempel , =?UTF-8?q?Nicol=C3=B2=20Veronese?= , Simon Horman , mwojtas@chromium.org, Antoine Tenart , devicetree@vger.kernel.org, Conor Dooley , Krzysztof Kozlowski , Rob Herring , Romain Gantois , Daniel Golle , Dimitri Fedrau , Tariq Toukan Subject: [PATCH net-next v20 14/14] Documentation: networking: Document the phy_port infrastructure Date: Thu, 27 Nov 2025 18:17:57 +0100 Message-ID: <20251127171800.171330-15-maxime.chevallier@bootlin.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251127171800.171330-1-maxime.chevallier@bootlin.com> References: <20251127171800.171330-1-maxime.chevallier@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 Content-Type: text/plain; charset="utf-8" This documentation aims at describing the main goal of the phy_port infrastructure. Reviewed-by: Christophe Leroy Reviewed-by: Andrew Lunn Tested-by: Christophe Leroy Signed-off-by: Maxime Chevallier --- Documentation/networking/index.rst | 1 + Documentation/networking/phy-port.rst | 111 ++++++++++++++++++++++++++ MAINTAINERS | 2 + 3 files changed, 114 insertions(+) create mode 100644 Documentation/networking/phy-port.rst diff --git a/Documentation/networking/index.rst b/Documentation/networking/= index.rst index 75db2251649b..49fcfa577711 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -96,6 +96,7 @@ Contents: packet_mmap phonet phy-link-topology + phy-port pktgen plip ppp_generic diff --git a/Documentation/networking/phy-port.rst b/Documentation/networki= ng/phy-port.rst new file mode 100644 index 000000000000..6e28d9094bce --- /dev/null +++ b/Documentation/networking/phy-port.rst @@ -0,0 +1,111 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _phy_port: + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +Ethernet ports +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +This document is a basic description of the phy_port infrastructure, +introduced to represent physical interfaces of Ethernet devices. + +Without phy_port, we already have quite a lot of information about what the +media-facing interface of a NIC can do and looks like, through the +:c:type:`struct ethtool_link_ksettings ` attribute= s, +which includes : + + - What the NIC can do through the :c:member:`supported` field + - What the Link Partner advertises through :c:member:`lp_advertising` + - Which features we're advertising through :c:member:`advertising` + +We also have info about the number of pairs and the PORT type. These setti= ngs +are built by aggregating together information reported by various devices = that +are sitting on the link : + + - The NIC itself, through the :c:member:`get_link_ksettings` callback + - Precise information from the MAC and PCS by using phylink in the MAC d= river + - Information reported by the PHY device + - Information reported by an SFP module (which can itself include a PHY) + +This model however starts showing its limitations when we consider devices= that +have more than one media interface. In such a case, only information about= the +actively used interface is reported, and it's not possible to know what the +other interfaces can do. In fact, we have very little information about wh= ether +or not there are any other media interfaces. + +The goal of the phy_port representation is to provide a way of representin= g a +physical interface of a NIC, regardless of what is driving the port (NIC t= hrough +a firmware, SFP module, Ethernet PHY). + +Multi-port interfaces examples +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D + +Several cases of multi-interface NICs have been observed so far : + +Internal MII Mux:: + + +------------------+ + | SoC | + | +-----+ | +-----+ + | +-----+ | |-------------| PHY | + | | MAC |--| Mux | | +-----+ +-----+ + | +-----+ | |-----| SFP | + | +-----+ | +-----+ + +------------------+ + +Internal Mux with internal PHY:: + + +------------------------+ + | SoC | + | +-----+ +-----+ + | +-----+ | |-| PHY | + | | MAC |--| Mux | +-----+ +-----+ + | +-----+ | |-----------| SFP | + | +-----+ | +-----+ + +------------------------+ + +External Mux:: + + +---------+ + | SoC | +-----+ +-----+ + | | | |--| PHY | + | +-----+ | | | +-----+ + | | MAC |----| Mux | +-----+ + | +-----+ | | |--| PHY | + | | +-----+ +-----+ + | | | + | GPIO-------+ + +---------+ + +Double-port PHY:: + + +---------+ + | SoC | +-----+ + | | | |--- RJ45 + | +-----+ | | | + | | MAC |---| PHY | +-----+ + | +-----+ | | |---| SFP | + +---------+ +-----+ +-----+ + +phy_port aims at providing a path to support all the above topologies, by +representing the media interfaces in a way that's agnostic to what's drivi= ng +the interface. the struct phy_port object has its own set of callback ops,= and +will eventually be able to report its own ksettings:: + + _____ +------+ + ( )-----| Port | + +-----+ ( ) +------+ + | MAC |--( ??? ) + +-----+ ( ) +------+ + (_____)-----| Port | + +------+ + +Next steps +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +As of writing this documentation, only ports controlled by PHY devices are +supported. The next steps will be to add the Netlink API to expose these +to userspace and add support for raw ports (controlled by some firmware, a= nd directly +managed by the NIC driver). + +Another parallel task is the introduction of a MII muxing framework to all= ow the +control of non-PHY driver multi-port setups. diff --git a/MAINTAINERS b/MAINTAINERS index 7e1489f33c40..3e9c80624888 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9282,6 +9282,7 @@ F: Documentation/devicetree/bindings/net/ethernet-con= nector.yaml F: Documentation/devicetree/bindings/net/ethernet-phy.yaml F: Documentation/devicetree/bindings/net/mdio* F: Documentation/devicetree/bindings/net/qca,ar803x.yaml +F: Documentation/networking/phy-port.rst F: Documentation/networking/phy.rst F: drivers/net/mdio/ F: drivers/net/mdio/acpi_mdio.c @@ -17980,6 +17981,7 @@ F: net/ethtool/phy.c NETWORKING [ETHTOOL PHY PORT] M: Maxime Chevallier F: Documentation/devicetree/bindings/net/ethernet-connector.yaml +F: Documentation/networking/phy-port.rst F: drivers/net/phy/phy_port.c F: include/linux/phy_port.h K: struct\s+phy_port|phy_port_ --=20 2.49.0