linux-kernel - [PATCH v2] of: address: Work around missing device

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Message-Id: <20200819094255.474565-1-maz@kernel.org>
Date:   Wed, 19 Aug 2020 10:42:55 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     devicetree@...r.kernel.org, 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,
        Frank Rowand <frowand.list@...il.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Rob Herring <robh+dt@...nel.org>
Subject: [PATCH v2] of: address: Work around missing device_type property in pcie nodes

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 it, let's add a workaround to the code
matching the device type, and accept as PCI any node that is
named "pcie",

A warning will hopefully nudge the user into updating their
DT to a fixed version if they can, but the incentive is
obviously pretty small.

Fixes: 2f96593ecc37 ("of_address: Add bus type match for pci ranges parser")
Suggested-by: Rob Herring <robh+dt@...nel.org>
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/of/address.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 590493e04b01..b37bd9cc2810 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -128,15 +128,29 @@ static unsigned int of_bus_pci_get_flags(const __be32 *addr)
  * PCI bus specific translator
  */
 
+static bool of_node_is_pcie(struct device_node *np)
+{
+	bool is_pcie = of_node_name_eq(np, "pcie");
+
+	if (is_pcie)
+		pr_warn_once("%pOF: Missing device_type\n", np);
+
+	return is_pcie;
+}
+
 static int of_bus_pci_match(struct device_node *np)
 {
 	/*
  	 * "pciex" is PCI Express
 	 * "vci" is for the /chaos bridge on 1st-gen PCI powermacs
 	 * "ht" is hypertransport
+	 *
+	 * If none of the device_type match, and that the node name is
+	 * "pcie", accept the device as PCI (with a warning).
 	 */
 	return of_node_is_type(np, "pci") || of_node_is_type(np, "pciex") ||
-		of_node_is_type(np, "vci") || of_node_is_type(np, "ht");
+		of_node_is_type(np, "vci") || of_node_is_type(np, "ht") ||
+		of_node_is_pcie(np);
 }
 
 static void of_bus_pci_count_cells(struct device_node *np,
-- 
2.27.0