| Message ID | 20170327094954.7162-5-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index bd98674..9e084c0 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3375,7 +3375,7 @@ int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr) return -EINVAL; return ioremap_page_range(vaddr, vaddr + resource_size(res), phys_addr, - pgprot_device(PAGE_KERNEL)); + pgprot_nonposted(PAGE_KERNEL)); #else /* this architecture does not have memory mapped I/O space, so this function should never be called */
According to the PCI local bus specifications (Revision 3.0, 3.2.5), I/O Address space transactions are non-posted. On architectures where I/O space is implemented through a chunk of memory mapped space mapped to PCI address space (ie IA64/ARM/ARM64) the memory mapping for the region backing I/O Address Space transactions determines the I/O transactions attributes (before the transactions actually reaches the PCI bus where it is handled according to the PCI specifications). Current pci_remap_iospace() interface, that is used to map the PCI I/O Address Space into virtual address space, use pgprot_device() as memory attribute for the virtual address mapping, that in some architectures (ie ARM64) provides non-cacheable but write bufferable mappings (ie posted writes), which clash with the non-posted write behaviour for I/O Address Space mandated by the PCI specifications. Update the prot ioremap_page_range() parameter in pci_remap_iospace() to pgprot_nonposted to ensure that the virtual mapping backing I/O Address Space guarantee non-posted write transactions issued when addressing I/O Address Space through the MMIO mapping. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Will Deacon <will.deacon@arm.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> --- drivers/pci/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)