cns3xxx: use actual size reads for PCIe

upstream commit 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
reimplemented cns3xxx_pci_read_config() using pci_generic_config_read32(),
which preserved the property of only doing 32-bit reads.

It also replaced cns3xxx_pci_write_config() with pci_generic_config_write(),
so it changed writes from always being 32 bits to being the actual size,
which works just fine.

Due to:
- The documentation does not mention that only 32 bit access is allowed.
- Writes are already executed using the actual size
- Extensive testing shows that 8b, 16b and 32b reads work as intended

It makes perfectly sense to also swap 32 bit reading in favor of actual size.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/generic/patches-4.4/107-arm-cns3xxx-use-actual-size-reads-for-PCIe.patch

@@ -0,0 +1,51 @@
+From 4cc30de79d293f1e8c5f50ae3a9c005def9564a0 Mon Sep 17 00:00:00 2001
+From: Koen Vandeputte <koen.vandeputte@ncentric.com>
+Date: Mon, 7 Jan 2019 14:14:27 +0100
+Subject: [PATCH 2/2] arm: cns3xxx: use actual size reads for PCIe
+
+commit 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
+reimplemented cns3xxx_pci_read_config() using pci_generic_config_read32(),
+which preserved the property of only doing 32-bit reads.
+
+It also replaced cns3xxx_pci_write_config() with pci_generic_config_write(),
+so it changed writes from always being 32 bits to being the actual size,
+which works just fine.
+
+Due to:
+- The documentation does not mention that only 32 bit access is allowed.
+- Writes are already executed using the actual size
+- Extensive testing shows that 8b, 16b and 32b reads work as intended
+
+It makes perfectly sense to also swap 32 bit reading in favor of actual size.
+
+Fixes: 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
+Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
+Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
+CC: Arnd Bergmann <arnd@arndb.de>
+CC: Krzysztof Halasa <khalasa@piap.pl>
+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>
+CC: Tim Harvey <tharvey@gateworks.com>
+CC: stable@vger.kernel.org # v4.0+
+---
+ arch/arm/mach-cns3xxx/pcie.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arm/mach-cns3xxx/pcie.c b/arch/arm/mach-cns3xxx/pcie.c
+index 5e11ad3164e0..95a11d5b3587 100644
+--- a/arch/arm/mach-cns3xxx/pcie.c
++++ b/arch/arm/mach-cns3xxx/pcie.c
+@@ -93,7 +93,7 @@ static int cns3xxx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
+ 	u32 mask = (0x1ull << (size * 8)) - 1;
+ 	int shift = (where % 4) * 8;
+ 
+-	ret = pci_generic_config_read32(bus, devfn, where, size, val);
++	ret = pci_generic_config_read(bus, devfn, where, size, val);
+ 
+ 	if (ret == PCIBIOS_SUCCESSFUL && !bus->number && !devfn &&
+ 	    (where & 0xffc) == PCI_CLASS_REVISION)
+-- 
+2.17.1
+