ARM: cns3xxx: Fix writing to wrong PCI config registers after alignment

Koen Vandeputte · bjorn-helgaas · commit 65dbb423cf28 · 2019-01-31T15:01:44.000-06:00
Originally, cns3xxx used its own functions for mapping, reading and writing config registers. Commit 802b7c0 ("ARM: cns3xxx: Convert PCI to use generic config accessors") removed the internal PCI config write function in favor of the generic one: cns3xxx_pci_write_config() --> pci_generic_config_write() cns3xxx_pci_write_config() expected aligned addresses, being produced by cns3xxx_pci_map_bus() while the generic one pci_generic_config_write() actually expects the real address as both the function and hardware are capable of byte-aligned writes. This currently leads to pci_generic_config_write() writing to the wrong registers. For instance, upon ath9k module loading: - driver ath9k gets loaded - The driver wants to write value 0xA8 to register PCI_LATENCY_TIMER, located at 0x0D - cns3xxx_pci_map_bus() aligns the address to 0x0C - pci_generic_config_write() effectively writes 0xA8 into register 0x0C (CACHE_LINE_SIZE) Fix the bug by removing the alignment in the cns3xxx mapping function. Fixes: 802b7c0 ("ARM: cns3xxx: Convert PCI to use generic config accessors") Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com> [lorenzo.pieralisi@arm.com: updated commit log] Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Krzysztof Halasa <khalasa@piap.pl> Acked-by: Tim Harvey <tharvey@gateworks.com> Acked-by: Arnd Bergmann <arnd@arndb.de> CC: stable@vger.kernel.org # v4.0+ CC: Bjorn Helgaas <bhelgaas@google.com> CC: Olof Johansson <olof@lixom.net> CC: Robin Leblon <robin.leblon@ncentric.com> CC: Rob Herring <robh@kernel.org> CC: Russell King <linux@armlinux.org.uk>
diff --git a/arch/arm/mach-cns3xxx/pcie.c b/arch/arm/mach-cns3xxx/pcie.c
@@ -83,7 +83,7 @@ static void __iomem *cns3xxx_pci_map_bus(struct pci_bus *bus,
 	} else /* remote PCI bus */
 		base = cnspci->cfg1_regs + ((busno & 0xf) << 20);
 
-	return base + (where & 0xffc) + (devfn << 12);
+	return base + where + (devfn << 12);
 }
 
 static int cns3xxx_pci_read_config(struct pci_bus *bus, unsigned int devfn,

Original file line number	Diff line number	Diff line change
`@@ -83,7 +83,7 @@ static void __iomem cns3xxx_pci_map_bus(struct pci_bus bus,`
`83`	`83`	`} else /* remote PCI bus */`
`84`	`84`	`base = cnspci->cfg1_regs + ((busno & 0xf) << 20);`
`85`	`85`
`86`		`- return base + (where & 0xffc) + (devfn << 12);`
	`86`	`+ return base + where + (devfn << 12);`
`87`	`87`	`}`
`88`	`88`
`89`	`89`	`static int cns3xxx_pci_read_config(struct pci_bus *bus, unsigned int devfn,`