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x86: restore old GART alloc_coherent behavior

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Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32
for a device having dma_masks > 24bit < 32bits. If GART gets an
address that a device can't access to, GART try to map the address to
a virtual I/O address that the device can access to.

But Andi pointed out, "The GART is somewhere in the 4GB range so you
cannot use it to map anything < 4GB. Also GART is pretty small."

http://lkml.org/lkml/2008/9/12/43

That is, it's possible that GART doesn't have virtual I/O address
space that a device can access to. The above behavior doesn't work for
a device having dma_masks > 24bit < 32bits.

This patch restores old GART alloc_coherent behavior (before the
alloc_coherent rewrite).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
FUJITA Tomonori 2008-09-24 20:48:37 +09:00 committed by Ingo Molnar
parent ecef533ea6
commit 1d99088215
1 changed files with 17 additions and 20 deletions
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37
arch/x86/kernel/pci-gart_64.c
View File

@ -487,31 +487,28 @@ static void *
gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
gfp_t flag)
{
void *vaddr;
dma_addr_t paddr;
unsigned long align_mask;
u64 dma_mask = dma_alloc_coherent_mask(dev, flag);
struct page *page;
vaddr = (void *)__get_free_pages(flag | __GFP_ZERO, get_order(size));
if (!vaddr)
return NULL;
if (force_iommu && !(flag & GFP_DMA)) {
flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
page = alloc_pages(flag | __GFP_ZERO, get_order(size));
if (!page)
return NULL;
paddr = virt_to_phys(vaddr);
if (is_buffer_dma_capable(dma_mask, paddr, size)) {
*dma_addr = paddr;
return vaddr;
}
align_mask = (1UL << get_order(size)) - 1;
paddr = dma_map_area(dev, page_to_phys(page), size,
DMA_BIDIRECTIONAL, align_mask);
align_mask = (1UL << get_order(size)) - 1;
*dma_addr = dma_map_area(dev, paddr, size, DMA_BIDIRECTIONAL,
align_mask);
flush_gart();
if (*dma_addr != bad_dma_address)
return vaddr;
free_pages((unsigned long)vaddr, get_order(size));
flush_gart();
if (paddr != bad_dma_address) {
*dma_addr = paddr;
return page_address(page);
}
__free_pages(page, get_order(size));
} else
return dma_generic_alloc_coherent(dev, size, dma_addr, flag);
return NULL;
}