linux-kernel - [PATCH v2] PCI: rcar-host: Add static assertion to check !PCI_LOCKLESS

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Message-ID: <20250923234644.82890-1-marek.vasut+renesas@mailbox.org>
Date: Wed, 24 Sep 2025 01:46:18 +0200
From: Marek Vasut <marek.vasut+renesas@...lbox.org>
To: linux-pci@...r.kernel.org
Cc: Marek Vasut <marek.vasut+renesas@...lbox.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Marek Vasut <marek.vasut+renesas@...il.com>,
	Rob Herring <robh@...nel.org>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org
Subject: [PATCH v2] PCI: rcar-host: Add static assertion to check !PCI_LOCKLESS_CONFIG

This driver can not function correctly without PCIe subsystem level
config space access serialization. In case PCI_LOCKLESS_CONFIG is
ever enabled on ARM, complain loudly so the driver can be updated
accordingly.

Signed-off-by: Marek Vasut <marek.vasut+renesas@...lbox.org>
---
Cc: "Krzysztof Wilczyński" <kwilczynski@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: Magnus Damm <magnus.damm@...il.com>
Cc: Manivannan Sadhasivam <mani@...nel.org>
Cc: Marek Vasut <marek.vasut+renesas@...il.com>
Cc: Rob Herring <robh@...nel.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-pci@...r.kernel.org
Cc: linux-renesas-soc@...r.kernel.org
---
V2: Add depends on !PCI_LOCKLESS_CONFIG into Kconfig file, to prevent
    this from being built when PCI_LOCKLESS_CONFIG is not set at all
---
 drivers/pci/controller/Kconfig          | 1 +
 drivers/pci/controller/pcie-rcar-host.c | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 41748d083b933..3f489bed289fb 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -244,6 +244,7 @@ config PCIE_RCAR_HOST
 	bool "Renesas R-Car PCIe controller (host mode)"
 	depends on ARCH_RENESAS || COMPILE_TEST
 	depends on PCI_MSI
+	depends on !PCI_LOCKLESS_CONFIG
 	select IRQ_MSI_LIB
 	help
 	  Say Y here if you want PCIe controller support on R-Car SoCs in host
diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c
index 213028052aa58..29e13f7ff7ff1 100644
--- a/drivers/pci/controller/pcie-rcar-host.c
+++ b/drivers/pci/controller/pcie-rcar-host.c
@@ -35,6 +35,14 @@
 
 #include "pcie-rcar.h"
 
+/*
+ * This driver can not function correctly without PCIe subsystem level
+ * config space access serialization. In case PCI_LOCKLESS_CONFIG is
+ * ever enabled on ARM, complain loudly so the driver can be updated
+ * accordingly.
+ */
+static_assert(!IS_ENABLED(CONFIG_PCI_LOCKLESS_CONFIG));
+
 struct rcar_msi {
 	DECLARE_BITMAP(used, INT_PCI_MSI_NR);
 	struct irq_domain *domain;
-- 
2.51.0