[PATCH 4.4 44/65] ARM: cns3xxx: Fix writing to wrong PCI config registers after alignment

From: Greg Kroah-Hartman
Date: Mon Feb 04 2019 - 05:42:14 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Koen Vandeputte <koen.vandeputte@xxxxxxxxxxxx>

commit 65dbb423cf28232fed1732b779249d6164c5999b upstream.

Originally, cns3xxx used its own functions for mapping, reading and
writing config registers.

Commit 802b7c06adc7 ("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

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

Fix the bug by removing the alignment in the cns3xxx mapping function.

Fixes: 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
Signed-off-by: Koen Vandeputte <koen.vandeputte@xxxxxxxxxxxx>
[lorenzo.pieralisi@xxxxxxx: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Acked-by: Krzysztof Halasa <khalasa@xxxxxxx>
Acked-by: Tim Harvey <tharvey@xxxxxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx # v4.0+
CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
CC: Olof Johansson <olof@xxxxxxxxx>
CC: Robin Leblon <robin.leblon@xxxxxxxxxxxx>
CC: Rob Herring <robh@xxxxxxxxxx>
CC: Russell King <linux@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/arm/mach-cns3xxx/pcie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- 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
} 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,