From: Guo Ren <ren_guo@xxxxxxxxx>
This bug is from commit: 2b070ccdf8c0 (fixup abiv2 mmap(... O_SYNC)
failed). In that patch we remove the _PAGE_SO for memory noncache
mapping and this will cause problem when drivers use dma descriptors
to control the transcations without dma_w/rmb().
After referencing other archs' implementation, pgprot_writecombine is
introduced for mmap(... O_SYNC).
Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx>
---
arch/csky/include/asm/pgtable.h | 10 ++++++++++
arch/csky/mm/ioremap.c | 6 ++----
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index c429a6f..fc19ba4 100644
--- a/arch/csky/include/asm/pgtable.h
+++ b/arch/csky/include/asm/pgtable.h
@@ -258,6 +258,16 @@ static inline pgprot_t pgprot_noncached(pgprot_t _prot)
{
unsigned long prot = pgprot_val(_prot);
+ prot = (prot & ~_CACHE_MASK) | _CACHE_UNCACHED | _PAGE_SO;
+
+ return __pgprot(prot);
+}
+
+#define pgprot_writecombine pgprot_writecombine
+static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
+{
+ unsigned long prot = pgprot_val(_prot);
+
prot = (prot & ~_CACHE_MASK) | _CACHE_UNCACHED;
return __pgprot(prot);
diff --git a/arch/csky/mm/ioremap.c b/arch/csky/mm/ioremap.c
index 8473b6b..4853111 100644
--- a/arch/csky/mm/ioremap.c
+++ b/arch/csky/mm/ioremap.c
@@ -29,8 +29,7 @@ void __iomem *ioremap(phys_addr_t addr, size_t size)
vaddr = (unsigned long)area->addr;
- prot = __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE |
- _PAGE_GLOBAL | _CACHE_UNCACHED | _PAGE_SO);
+ prot = pgprot_noncached(PAGE_KERNEL);
if (ioremap_page_range(vaddr, vaddr + size, addr, prot)) {
free_vm_area(area);
@@ -51,10 +50,9 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{
if (!pfn_valid(pfn)) {
- vma_prot.pgprot |= _PAGE_SO;
return pgprot_noncached(vma_prot);
} else if (file->f_flags & O_SYNC) {
- return pgprot_noncached(vma_prot);
+ return pgprot_writecombine(vma_prot);
}
return vma_prot;
--
2.7.4
