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Subject[PATCH v2 24/27] ia64: Remove redundant checks for WC in pci_mmap_page_range()
Date
From: David Woodhouse <dwmw@amazon.co.uk>

For a PCI MMIO BAR, phys_mem_access_prot() should always return UC or WC.
And while a mixture of cached and uncached mappings is forbidden, we were
already mixing WC and UC, which is OK. Just do as we're asked.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
arch/ia64/pci/pci.c | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/arch/ia64/pci/pci.c b/arch/ia64/pci/pci.c
index 27020f3..7438e8c 100644
--- a/arch/ia64/pci/pci.c
+++ b/arch/ia64/pci/pci.c
@@ -423,9 +423,6 @@ pci_mmap_page_range (struct pci_dev *dev, int bar,
struct vm_area_struct *vma,
enum pci_mmap_state mmap_state, int write_combine)
{
- unsigned long size = vma->vm_end - vma->vm_start;
- pgprot_t prot;
-
/*
* I/O space cannot be accessed via normal processor loads and
* stores on this platform.
@@ -439,21 +436,10 @@ pci_mmap_page_range (struct pci_dev *dev, int bar,
*/
return -EINVAL;

- prot = phys_mem_access_prot(NULL, vma->vm_pgoff, size,
- vma->vm_page_prot);
-
- /*
- * If the user requested WC, the kernel uses UC or WC for this region,
- * and the chipset supports WC, we can use WC. Otherwise, we have to
- * use the same attribute the kernel uses.
- */
- if (write_combine &&
- ((pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_UC ||
- (pgprot_val(prot) & _PAGE_MA_MASK) == _PAGE_MA_WC) &&
- efi_range_is_wc(vma->vm_start, vma->vm_end - vma->vm_start))
+ if (write_combine)
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
else
- vma->vm_page_prot = prot;
+ vma->vm_page_prot = pgprot_device(vma->vm_page_prot);

if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot))
--
2.9.3
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