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author | Yinghai Lu <yinghai@kernel.org> | 2016-06-17 21:43:33 +0200 |
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committer | Bjorn Helgaas <bhelgaas@google.com> | 2016-06-17 21:43:33 +0200 |
commit | 1e70cdd6e654a66b4f6296a92cd0f7c265a02429 (patch) | |
tree | e345910b45b4ea6bdc2fe481d9ff7d4a5012ae9d /arch | |
parent | PCI: Ignore write combining when mapping I/O port space (diff) | |
download | linux-1e70cdd6e654a66b4f6296a92cd0f7c265a02429.tar.xz linux-1e70cdd6e654a66b4f6296a92cd0f7c265a02429.zip |
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>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/powerpc/kernel/pci-common.c | 37 |
1 files changed, 4 insertions, 33 deletions
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c index 0f7a60f1e9f6..8c6beb0229fe 100644 --- a/arch/powerpc/kernel/pci-common.c +++ b/arch/powerpc/kernel/pci-common.c @@ -356,36 +356,6 @@ static struct resource *__pci_mmap_make_offset(struct pci_dev *dev, } /* - * Set vm_page_prot of VMA, as appropriate for this architecture, for a pci - * device mapping. - */ -static pgprot_t __pci_mmap_set_pgprot(struct pci_dev *dev, struct resource *rp, - pgprot_t protection, - enum pci_mmap_state mmap_state, - int write_combine) -{ - - /* Write combine is always 0 on non-memory space mappings. On - * memory space, if the user didn't pass 1, we check for a - * "prefetchable" resource. This is a bit hackish, but we use - * this to workaround the inability of /sysfs to provide a write - * combine bit - */ - if (mmap_state != pci_mmap_mem) - write_combine = 0; - else if (write_combine == 0) { - if (rp->flags & IORESOURCE_PREFETCH) - write_combine = 1; - } - - /* XXX would be nice to have a way to ask for write-through */ - if (write_combine) - return pgprot_noncached_wc(protection); - else - return pgprot_noncached(protection); -} - -/* * This one is used by /dev/mem and fbdev who have no clue about the * PCI device, it tries to find the PCI device first and calls the * above routine @@ -458,9 +428,10 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma, return -EINVAL; vma->vm_pgoff = offset >> PAGE_SHIFT; - vma->vm_page_prot = __pci_mmap_set_pgprot(dev, rp, - vma->vm_page_prot, - mmap_state, write_combine); + if (write_combine) + vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot); + else + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); ret = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, vma->vm_end - vma->vm_start, vma->vm_page_prot); |