linux-kernel - [PATCH v2 1/4] PCI: rockchip: limit RK3399 to 2.5 GT/s to prevent damage

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Message-ID: <eaa9c75ca02a53f8bcc293b8bc73d013e26ec253.1763415706.git.geraldogabriel@gmail.com>
Date: Mon, 17 Nov 2025 18:47:05 -0300
From: Geraldo Nascimento <geraldogabriel@...il.com>
To: Shawn Lin <shawn.lin@...k-chips.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Johan Jonker <jbx6244@...il.com>,
	Geraldo Nascimento <geraldogabriel@...il.com>,
	Dragan Simic <dsimic@...jaro.org>
Cc: linux-rockchip@...ts.infradead.org, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: [PATCH v2 1/4] PCI: rockchip: limit RK3399 to 2.5 GT/s to prevent
 damage

Shawn Lin from Rockchip has reiterated that there may be danger in using
their PCIe with 5.0 GT/s speeds. Warn the user if they make a DT change
from the default and drive at 2.5 GT/s only, even if the DT
max-link-speed property is invalid or inexistent.

This change is corroborated by RK3399 official datasheet [1], which
says maximum link speed for this platform is 2.5 GT/s.

[1] https://opensource.rock-chips.com/images/d/d7/Rockchip_RK3399_Datasheet_V2.1-20200323.pdf

Fixes: 956cd99b35a8 ("PCI: rockchip: Separate common code from RC driver")
Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
Cc: stable@...r.kernel.org
Reported-by: Dragan Simic <dsimic@...jaro.org>
Reported-by: Shawn Lin <shawn.lin@...k-chips.com>
Reviewed-by: Dragan Simic <dsimic@...jaro.org>
Signed-off-by: Geraldo Nascimento <geraldogabriel@...il.com>
---
 drivers/pci/controller/pcie-rockchip.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip.c b/drivers/pci/controller/pcie-rockchip.c
index 0f88da378805..992ccf4b139e 100644
--- a/drivers/pci/controller/pcie-rockchip.c
+++ b/drivers/pci/controller/pcie-rockchip.c
@@ -66,8 +66,14 @@ int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 	}
 
 	rockchip->link_gen = of_pci_get_max_link_speed(node);
-	if (rockchip->link_gen < 0 || rockchip->link_gen > 2)
-		rockchip->link_gen = 2;
+	if (rockchip->link_gen < 0 || rockchip->link_gen > 2) {
+		rockchip->link_gen = 1;
+		dev_warn(dev, "invalid max-link-speed, set to 2.5 GT/s\n");
+	}
+	else if (rockchip->link_gen == 2) {
+		rockchip->link_gen = 1;
+		dev_warn(dev, "5.0 GT/s is dangerous, set to 2.5 GT/s\n");
+	}
 
 	for (i = 0; i < ROCKCHIP_NUM_PM_RSTS; i++)
 		rockchip->pm_rsts[i].id = rockchip_pci_pm_rsts[i];
-- 
2.49.0