[PATCH 2/2] dma: change coherent memory to normal noncached
Abhijeet Dharmapurikar
adharmap at codeaurora.org
Fri Nov 20 15:29:11 EST 2009
We need dma_alloc_coherent() to use its own page protection modifier,
which causes it to behave the same as dma_alloc_writecombine() on ARMv7,
and with the existing behaviour (for the time being) on ARMv6 and below.
We should leave pgprot_noncached() well alone until we know that its
other places need to be changed.
Signed-off-by: Abhijeet Dharmapurikar <adharmap at codeaurora.org>
---
arch/arm/include/asm/pgtable.h | 15 +++++++++++++--
arch/arm/mm/dma-mapping.c | 4 ++--
2 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index a27ec4c..0fd8d83 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -307,16 +307,27 @@ PTE_BIT_FUNC(mkyoung, |= L_PTE_YOUNG);
static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
+#define __pgprot_modify(prot, mask, bits) \
+ __pgprot((pgprot_val(prot) & ~(mask)) | (bits))
+
/*
* Mark the prot value as uncacheable and unbufferable.
*/
#define pgprot_noncached(prot) \
- __pgprot((pgprot_val(prot) & ~L_PTE_MT_MASK) | L_PTE_MT_UNCACHED)
+ __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)
#define pgprot_writecombine(prot) \
- __pgprot((pgprot_val(prot) & ~L_PTE_MT_MASK) | L_PTE_MT_BUFFERABLE)
+ __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE)
#define pgprot_device(prot) \
__pgprot((pgprot_val(prot) & ~L_PTE_MT_MASK) | L_PTE_MT_DEV_NONSHARED)
+#if __LINUX_ARM_ARCH__ >= 7
+#define pgprot_dmacoherent(prot) \
+ __pgprot_modify(prot, L_PTE_MT_MASK|L_PTE_EXEC, L_PTE_MT_BUFFERABLE)
+#else
+#define pgprot_dmacoherent(prot) \
+ __pgprot_modify(prot, L_PTE_MT_MASK|L_PTE_EXEC, L_PTE_MT_UNCACHED)
+#endif
+
#define pmd_none(pmd) (!pmd_val(pmd))
#define pmd_present(pmd) (pmd_val(pmd))
#define pmd_bad(pmd) (pmd_val(pmd) & 2)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 0b38ec8..8e2ff87 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -291,7 +291,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gf
}
return __dma_alloc(dev, size, handle, gfp,
- pgprot_noncached(pgprot_kernel));
+ pgprot_dmacoherent(pgprot_kernel));
}
EXPORT_SYMBOL(dma_alloc_coherent);
@@ -340,7 +340,7 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
}
EXPORT_SYMBOL(dma_mmap_coherent);
--
1.5.6.3
More information about the linux-arm-kernel
mailing list