Commit 7f80fe20 authored by Guo Ren's avatar Guo Ren
Browse files

csky: Fixup dma_alloc_coherent with PAGE_SO attribute 



This bug is from commit: 2b070ccd (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: default avatarGuo Ren <ren_guo@c-sky.com>
parent 81b23ba6

arch/csky/include/asm/pgtable.h

+10 −0
Original line number Diff line number Diff line
@@ -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);

arch/csky/mm/ioremap.c

+2 −4
Original line number Diff line number Diff line
@@ -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;

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