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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uWGAG-00000002hf7-1A9I; Mon, 30 Jun 2025 15:11:24 +0000 Received: from relay5-d.mail.gandi.net ([217.70.183.197]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uWFZr-00000002aJS-3bj0 for linux-arm-kernel@lists.infradead.org; Mon, 30 Jun 2025 14:33:49 +0000 Received: by mail.gandi.net (Postfix) with ESMTPSA id D553644318; Mon, 30 Jun 2025 14:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1751294026; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Apu6uy+C7r9DZpfPo98S0/i/narg5WnjIZELOVTCkSI=; b=aAzFqWMXD1X9xkCWnHzTWkW3Xcsmpy7473yg4fIS7lsbpC7HfaNpfTevcyoYFlj+S/Q0Qt 7N8w5T/ONlh+9if4nXYORdmB+MkdiYsoEkMXOTlwCoxiRGziJrWLfOCgrW7N3b95t40Kod QQ634oc9eXpRgebWgPkyLV2KTWQO0gm7fW+XnN9FG4azLMtrGX/fx5ScR5lx+RbqijBAJJ qIW8l1TyijL+ocOOv4mcpSFAWWB6cqP49/uqUA6Gs9hnpdhOaahnt/7KCL7p1uj+nEGvww fXNfhKI3/RfqMrboVk4UpPbpksLucbG14kSq1PtmNKa3p82oF2tsrUCxWYKy6g== 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 Subject: [PATCH net-next v7 15/15] Documentation: networking: Document the phy_port infrastructure Date: Mon, 30 Jun 2025 16:33:14 +0200 Message-ID: <20250630143315.250879-16-maxime.chevallier@bootlin.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250630143315.250879-1-maxime.chevallier@bootlin.com> References: <20250630143315.250879-1-maxime.chevallier@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgdduudelhecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepofgrgihimhgvucevhhgvvhgrlhhlihgvrhcuoehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeevgedtffelffelveeuleelgfejfeevvdejhfehgeefgfffvdefteegvedutefftdenucfkphepvdgrtddumegtsgduleemkegugeehmeegledttdemieehieekmedvlegsudemlegvfhehmegvkegtjeenucevlhhushhtvghrufhiiigvpedufeenucfrrghrrghmpehinhgvthepvdgrtddumegtsgduleemkegugeehmeegledttdemieehieekmedvlegsudemlegvfhehmegvkegtjedphhgvlhhopehfvgguohhrrgdrhhhomhgvpdhmrghilhhfrhhomhepmhgrgihimhgvrdgthhgvvhgrlhhlihgvrhessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepfedupdhrtghpthhtohepuggrvhgvmhesuggrvhgvmhhlohhfthdrnhgvthdprhgtphhtthhopehmrgigihhmvgdrtghhvghvrghllhhivghrsegsohhothhlihhnrdgtohhmpdhrtghpthhtohepnhgvthguvghvsehvghgvrhdrk hgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqrghrmhdqmhhsmhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehthhhomhgrshdrphgvthgriiiiohhnihessghoohhtlhhinhdrtghomhdprhgtphhtthhopegrnhgurhgvfieslhhunhhnrdgthhdprhgtphhtthhopehkuhgsrgeskhgvrhhnvghlrdhorhhg X-GND-Sasl: maxime.chevallier@bootlin.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250630_073348_033825_1ADF04DD X-CRM114-Status: GOOD ( 20.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This documentation aims at describing the main goal of the phy_port infrastructure. Signed-off-by: Maxime Chevallier --- Documentation/networking/index.rst | 1 + Documentation/networking/phy-port.rst | 111 ++++++++++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 113 insertions(+) create mode 100644 Documentation/networking/phy-port.rst diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index ac90b82f3ce9..f60acc06e3f7 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/networking/phy-port.rst new file mode 100644 index 000000000000..6d9d46ebe438 --- /dev/null +++ b/Documentation/networking/phy-port.rst @@ -0,0 +1,111 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _phy_port: + +================= +Ethernet ports +================= + +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 ` attributes, +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 lanes and the PORT type. These settings +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 driver + - 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 few information about whether or +not there are any other media interfaces. + +The goal of the phy_port representation is to provide a way of representing a +physical interface of a NIC, regardless of what is driving the port (NIC through +a firmware, SFP module, Ethernet PHY). + +Multi-port interfaces examples +============================== + +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 driving +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 +========== + +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, and directly +managed by the NIC driver). + +Another parallel task is the introduction of a MII muxing framework to allow the +control of non-PHY driver multi-port setups. diff --git a/MAINTAINERS b/MAINTAINERS index 10d7548d440e..2db2b0d22c6a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8950,6 +8950,7 @@ F: Documentation/devicetree/bindings/net/ethernet-connector.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 -- 2.49.0