powerpc/pci: Remove __pci_mmap_set_pgprot()
The powerpc-specific __pci_mmap_set_pgprot() does two things:
1) Disables write combining for I/O port space mappings
This only affects procfs mappings. The pci_mmap_resource() sysfs path
only requests write combining for resources with IORESOURCE_PREFETCH
set, which doesn't include I/O resources.
The only way to request write combining for I/O port space mappings
was via the PCIIOC_WRITE_COMBINE ioctl and the proc_bus_pci_mmap()
path, and we recently changed that path to ignore write combining for
I/O, so this code in powerpc is no longer needed.
2) Automatically enables write combining for mappings of prefetchable
resources, even if not requested by the user
Both procfs (via PCIIOC_MMAP_IS_MEM and PCIIOC_WRITE_COMBINE ioctls)
and sysfs (via "resourceN_wc" files, which are created for resources
with IORESOURCE_PREFETCH) provide ways for the user to map PCI memory
space with write combining.
Users that desire write combining should use one of those ways instead
of relying on powerpc-specific behavior.
Remove the powerpc-specific __pci_mmap_set_pgprot().
The user-visible effect of this change is that powerpc users mapping
prefetchable PCI memory space via procfs without PCIIOC_WRITE_COMBINE or
via sysfs "resourceN" (not "resourceN_wc") will get regular uncacheable
mappings instead of the write combining mappings they used to get.
The new behavior matches the behavior on all other arches that support
write combining mapping.
[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
1 file changed