csky: Fixup dma_alloc_coherent with PAGE_SO attribute

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@c-sky.com>

diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index c429a6f..fc19ba4 100644 (file)
--- 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 (file)
--- 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;