linux-kernel - [PATCH 1/2] PCI: rockchip: Work around missing device

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Message-Id: <20200815125112.462652-2-maz@kernel.org>
Date:   Sat, 15 Aug 2020 13:51:11 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     linux-pci@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Shawn Lin <shawn.lin@...k-chips.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Heiko Stuebner <heiko@...ech.de>, kernel-team@...roid.com,
        Roh Herring <robh+dt@...nel.org>
Subject: [PATCH 1/2] PCI: rockchip: Work around missing device_type property in DT

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@...nel.org>
Signed-off-by: Marc Zyngier <maz@...nel.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