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From: Marc Zyngier <maz@kernel.org>
To: linux-pci@vger.kernel.org, linux-rockchip@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Heiko Stuebner <heiko@sntech.de>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	Roh Herring <robh+dt@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	kernel-team@android.com
Subject: [PATCH 1/2] PCI: rockchip: Work around missing device_type property in DT
Date: Sat, 15 Aug 2020 13:51:11 +0100
Message-ID: <20200815125112.462652-2-maz@kernel.org> (raw)
In-Reply-To: <20200815125112.462652-1-maz@kernel.org>

Recent changes to the DT PCI bus parsing made it mandatory for
device tree nodes describing a PCI controller to have the
'device_type = "pci"' property for the node to be matched.

Although this follows the letter of the specification, it
breaks existing device-trees that have been working fine
for years.  Rockchip rk3399-based systems are a prime example
of such collateral damage, and have stopped discovering their
PCI bus.

In order to paper over the blunder, let's add a workaround
to the pcie-rockchip driver, adding the missing property when
none is found at boot time. A warning will hopefully nudge the
user into updating their DT to a fixed version if they can, but
the insentive is obviously pretty small.

Fixes: 2f96593ecc37 ("of_address: Add bus type match for pci ranges parser")
Suggested-by: Roh Herring <robh+dt@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/pci/controller/pcie-rockchip-host.c | 29 +++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index 0bb2fb3e8a0b..d7dd04430a99 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -949,6 +949,35 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	if (!dev->of_node)
 		return -ENODEV;
 
+	/*
+	 * Most rk3399 DTs are missing the 'device_type = "pci"' property,
+	 * potentially leading to PCIe probing failure. Be kind to the
+	 * users and fix it up for them. Upgrading is recommended.
+	 */
+	if (!of_find_property(dev->of_node, "device_type", NULL)) {
+		const char dtype[] = "pci";
+		struct property *prop;
+
+		dev_warn(dev, "Working around missing device_type property\n");
+
+		prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+		if (!prop)
+			return -ENOMEM;
+
+		prop->name	= kstrdup("device_type", GFP_KERNEL);
+		prop->value	= kstrdup(dtype, GFP_KERNEL);
+		prop->length	= ARRAY_SIZE(dtype);
+		if (!prop->name || !prop->value) {
+			kfree(prop->name);
+			kfree(prop->value);
+			kfree(prop);
+			return -ENOMEM;
+		}
+
+		if (of_add_property(dev->of_node, prop))
+			dev_warn(dev, "Failed to add property, probing may fail");
+	}
+
 	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rockchip));
 	if (!bridge)
 		return -ENOMEM;
-- 
2.27.0


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Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-15 12:51 [PATCH 0/2] PCI: rockchip: Fix PCIe probing in 5.9 Marc Zyngier
2020-08-15 12:51 ` Marc Zyngier [this message]
2020-08-15 23:22   ` [PATCH 1/2] PCI: rockchip: Work around missing device_type property in DT Bjorn Helgaas
2020-08-16 10:39     ` Marc Zyngier
2020-08-17 16:12       ` Rob Herring
2020-08-18  7:35         ` Marc Zyngier
2020-08-18 14:23           ` Rob Herring
2020-08-18 17:34             ` Marc Zyngier
2020-08-18 17:48               ` Saravana Kannan
2020-08-18 19:02                 ` Marc Zyngier
2020-08-18 19:06                   ` Rob Herring
2020-08-15 12:51 ` [PATCH 2/2] arm64: dts: rockchip: Fix PCIe DT properties Marc Zyngier
2021-01-09 15:39 ` (subset) [PATCH 0/2] PCI: rockchip: Fix PCIe probing in 5.9 Heiko Stuebner

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