linux-kernel - [PATCH v6 1/1] PCI: of: Remove max-link-speed generation validation

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Message-Id: <20251218132036.308094-1-18255117159@163.com>
Date: Thu, 18 Dec 2025 21:20:36 +0800
From: Hans Zhang <18255117159@....com>
To: bhelgaas@...gle.com,
	helgaas@...nel.org
Cc: mani@...nel.org,
	ilpo.jarvinen@...ux.intel.com,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Hans Zhang <18255117159@....com>
Subject: [PATCH v6 1/1] PCI: of: Remove max-link-speed generation validation

The current implementation of of_pci_get_max_link_speed() validates
max-link-speed property values to be in the range 1~4 (Gen1~Gen4).
However, this creates maintenance overhead as each new PCIe generation
requires updating this validation logic.

Since device tree binding validation already enforces the allowed
values through the schema, and the callers of this function perform
their own validation checks, this intermediate validation becomes
redundant.

Furthermore, with upcoming SOCs using Synopsys/Cadence IP requiring
Gen5/Gen6 support, removing this hardcoded check enables seamless
support for future PCIe generations without requiring kernel updates
for each new speed grade.

Remove the max-link-speed > 4 validation check while retaining the
property existence and non-zero check. This simplifies maintenance
and aligns with the existing validation architecture where DT binding
and driver-level checks provide sufficient validation.

Signed-off-by: Hans Zhang <18255117159@....com>
Acked-by: Manivannan Sadhasivam <mani@...nel.org>
---
Changes for v6:
- It'd be good to return the actual errno as of_property_read_u32() can return
  -EINVAL, -ENODATA and -EOVERFLOW. (Mani)

Changes for v5:
https://patchwork.kernel.org/project/linux-pci/patch/20251218125909.305300-1-18255117159@163.com/

- Delete the check for speed. (Mani)

Changes for v4:
https://patchwork.kernel.org/project/linux-pci/patch/20251105134701.182795-1-18255117159@163.com/

- Add pcie_max_supported_link_speed.(Ilpo)

Changes for v3:
https://patchwork.kernel.org/project/linux-pci/patch/20251101164132.14145-1-18255117159@163.com/

- Modify the commit message.
- Add Reviewed-by tag.

Changes for v2:
https://patchwork.kernel.org/project/linux-pci/cover/20250529021026.475861-1-18255117159@163.com/
- The following files have been deleted:
  Documentation/devicetree/bindings/pci/pci.txt

  Update to this file again:
  dtschema/schemas/pci/pci-bus-common.yaml
---
 drivers/pci/of.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 3579265f1198..b56fdbcb3d72 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -888,10 +888,11 @@ bool of_pci_supply_present(struct device_node *np)
 int of_pci_get_max_link_speed(struct device_node *node)
 {
 	u32 max_link_speed;
+	int ret;

-	if (of_property_read_u32(node, "max-link-speed", &max_link_speed) ||
-	    max_link_speed == 0 || max_link_speed > 4)
-		return -EINVAL;
+	ret = of_property_read_u32(node, "max-link-speed", &max_link_speed);
+	if (ret)
+		return ret;

 	return max_link_speed;
 }
-- 
2.34.1