Commit 1c8c3cf0 authored May 19, 2014 by Thomas Petazzoni Committed by Russell King Jun 01, 2014

ARM: 8060/1: mm: allow sub-architectures to override PCI I/O memory type



Due to a design incompatibility between the PCIe Marvell controller
and the Cortex-A9, stressing PCIe devices with a lot of traffic
quickly causes a deadlock.

One part of the workaround for this is to have all PCIe regions mapped
as strongly-ordered (MT_UNCACHED) instead of the default
MT_DEVICE. While the arch_ioremap_caller() mechanism allows
sub-architecture code to override ioremap(), used to map PCIe memory
regions, there isn't such a mechanism to override the behavior of
pci_ioremap_io().

This commit adds the arch_pci_ioremap_mem_type variable, initialized
to MT_DEVICE by default, and that sub-architecture code can
override. We have chosen to expose a single variable rather than
offering the possibility of overriding the entire pci_ioremap_io(),
because implementing pci_ioremap_io() requires calling functions
(get_mem_type()) that are private to the arch/arm/mm/ code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent 437b680a

arch/arm/include/asm/io.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -179,6 +179,12 @@ static inline void __iomem *__typesafe_io(unsigned long addr)
		/* PCI fixed i/o mapping */
		#define PCI_IO_VIRT_BASE 0xfee00000

		#if defined(CONFIG_PCI)
		void pci_ioremap_set_mem_type(int mem_type);
		#else
		static inline void pci_ioremap_set_mem_type(int mem_type) {}
		#endif

		extern int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr);

		/*

arch/arm/mm/ioremap.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -438,6 +438,13 @@ void __arm_iounmap(volatile void __iomem *io_addr)
		EXPORT_SYMBOL(__arm_iounmap);

		#ifdef CONFIG_PCI
		static int pci_ioremap_mem_type = MT_DEVICE;

		void pci_ioremap_set_mem_type(int mem_type)
		{
		pci_ioremap_mem_type = mem_type;
		}

		int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr)
		{
		BUG_ON(offset + SZ_64K > IO_SPACE_LIMIT);
		@@ -445,7 +452,7 @@ int pci_ioremap_io(unsigned int offset, phys_addr_t phys_addr)
		return ioremap_page_range(PCI_IO_VIRT_BASE + offset,
		PCI_IO_VIRT_BASE + offset + SZ_64K,
		phys_addr,
		__pgprot(get_mem_type(MT_DEVICE)->prot_pte));
		__pgprot(get_mem_type(pci_ioremap_mem_type)->prot_pte));
		}
		EXPORT_SYMBOL_GPL(pci_ioremap_io);
		#endif

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