openwrt/target/linux/generic/backport-4.9/101-arm-cns3xxx-use-actual-size-reads-for-PCIe.patch

From 4cc30de79d293f1e8c5f50ae3a9c005def9564a0 Mon Sep 17 00:00:00 2001
From: Koen Vandeputte <[email protected]>
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 <[email protected]>
Signed-off-by: Koen Vandeputte <[email protected]>
CC: Arnd Bergmann <[email protected]>
CC: Krzysztof Halasa <[email protected]>
CC: Olof Johansson <[email protected]>
CC: Robin Leblon <[email protected]>
CC: Rob Herring <[email protected]>
CC: Russell King <[email protected]>
CC: Tim Harvey <[email protected]>
CC: [email protected] # 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