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

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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>
This commit is contained in:
Thomas Petazzoni 2014-05-19 11:04:39 +01:00 committed by Russell King
parent 437b680a22
commit 1c8c3cf0b5
2 changed files with 14 additions and 1 deletions
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6
arch/arm/include/asm/io.h
View File

@ -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);
/*

9
arch/arm/mm/ioremap.c
View File

@ -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