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Mon, 31 Aug 2026 18:13:46 -0700 (PDT) From: Alex Elder To: bhelgaas@google.com, robh@kernel.org, saravanak@kernel.org Cc: herve.codina@bootlin.com, daniel@riscstar.com, mohd.anwar@oss.qualcomm.com, lorenzo.bianconi@oss.qualcomm.com, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/4] PCI: of: introduce of_pci_verify_node() Date: Mon, 31 Aug 2026 20:13:36 -0500 Message-ID: <20260901011338.1323243-4-elder@riscstar.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260901011338.1323243-1-elder@riscstar.com> References: <20260901011338.1323243-1-elder@riscstar.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit 407d1a51921e9 ("PCI: Create device tree node for bridge") linked the PCI enumeration process together with devicetree, creating a devicetree node for discovered PCI bridges. Its successor commit ae9813db1dc5a ("PCI: Add quirks to generate device tree node for Xilinx Alveo U50") shows how to use a PCI final fixup quirk to also create a devicetree node for a non-bridge PCI device. These changes allowed devicetree overlays to describe components downstream of a PCI device, by providing a place to attach the overlay. Note that the dynamic devicetree node is only created if the device didn't already have an assigned node. Later, commit aa7b4bbcb3a1d ("arm64: dts: qcom: qcs6490-rb3gen2: Add TC9563 PCIe switch node") *pre-defined* devicetree nodes to represent the PCI device nodes that would (also) be discovered via the PCI enumeration process. The devicetree node in this case is created with the content from the DTS file. So when a (host) bridge is done being initialized during PCI enumeration, no node is dynamically created (the commits mentioned above do not apply). Ideally, any pre-defined PCI devicetree node would contain exactly the same information as whatever the dynamic creation process would produce (though it could include more). However that is not the case for the pre-defined Qualcomm RB3gen2 nodes. And in particular, the endpoint (function) nodes include this property: device_type = "pci"; This is simply wrong; that property is meant only for bridge nodes. Rob Herring requested that a runtime check to be added to spot this specific error, only for non-bridge PCI devices. Herve Codina further suggested we ensure that bridge PCI devices *do* define the device_type property, with value "pci". Signed-off-by: Alex Elder --- v3: - Switch a function header to use kernel-doc format - Add a warning if a PCI bridge node has no device_type property drivers/pci/bus.c | 1 + drivers/pci/of.c | 31 +++++++++++++++++++++++++++++++ drivers/pci/pci.h | 3 +++ 3 files changed, 35 insertions(+) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 655ed53436d3e..679afbc6d3109 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -351,6 +351,7 @@ void pci_bus_add_device(struct pci_dev *dev) * are not assigned yet for some devices. */ pcibios_bus_add_device(dev); + of_pci_verify_node(dev); pci_fixup_device(pci_fixup_final, dev); if (pci_is_bridge(dev)) of_pci_make_dev_node(dev); diff --git a/drivers/pci/of.c b/drivers/pci/of.c index a51dff91b196d..1838a3109514c 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -1085,3 +1085,34 @@ int of_pci_get_equalization_presets(struct device *dev, return 0; } EXPORT_SYMBOL_GPL(of_pci_get_equalization_presets); + +/** + * of_pci_verify_node - Sanity check some PCI device node properties + * @pdev: The PCI device whose device node is checked + * + * PCI enumeration authoritatively discovers what we need to know about + * a PCI device. A devicetree-based platform will represent a PCI root + * bridge with a node, but otherwise devicetree doesn't typically include + * many PCI nodes. Where such nodes do exist, experience has shown that + * the "device_type" property is sometimes wrong, so warn about that. + */ +void of_pci_verify_node(struct pci_dev *pdev) +{ + struct device_node *np = pci_device_to_OF_node(pdev); + bool device_is_bridge; + bool device_type_pci; + + /* Nothing to check if there's no pre-existing devicetree node */ + if (!np) + return; + + device_is_bridge = pci_is_bridge(pdev); + device_type_pci = of_node_is_type(np, "pci"); + + /* Bridges should have device type "pci"; endpoints should not */ + if (device_is_bridge == device_type_pci) + return; + + dev_err(&pdev->dev, "PCI %s have \"pci\" device_type property\n", + device_is_bridge ? "bridge should" : "endpoint should not"); +} diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index ba3c3fddddc23..2e33d3bd4b0ba 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -1253,6 +1253,7 @@ bool of_pci_supply_present(struct device_node *np); int of_pci_get_equalization_presets(struct device *dev, struct pci_eq_presets *presets, int num_lanes); +void of_pci_verify_node(struct pci_dev *pdev); #else static inline int of_get_pci_domain_nr(struct device_node *node) @@ -1308,6 +1309,8 @@ static inline int of_pci_get_equalization_presets(struct device *dev, return 0; } + +static inline void of_pci_verify_node(struct pci_dev *pdev) { } #endif /* CONFIG_OF */ struct of_changeset; -- 2.53.0