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SubjectRe: [PATCH 1/8] x86: add alloc_coherent dma_ops callback to GART driver
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On Tue, 19 Aug 2008 16:32:39 +0200
Joerg Roedel <joerg.roedel@amd.com> wrote:

> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
> ---
> arch/x86/kernel/pci-gart_64.c | 21 +++++++++++++++++++++
> 1 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
> index 4d8efb0..44a75a6 100644
> --- a/arch/x86/kernel/pci-gart_64.c
> +++ b/arch/x86/kernel/pci-gart_64.c
> @@ -506,6 +506,26 @@ error:
> return 0;
> }
>
> +/* allocate and map a coherent mapping */
> +static void *
> +gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
> + gfp_t flag)
> +{
> + void *vaddr;
> +
> + vaddr = (void *)__get_free_pages(flag, get_order(size));
> + if (!vaddr)
> + return NULL;
> +
> + *dma_addr = gart_map_single(dev, __pa(vaddr), size, DMA_BIDIRECTIONAL);
> + if (*dma_addr != bad_dma_address)
> + return vaddr;

I'm not sure a rule is documented or not, but I think that IOMMUs
return zeroed memory wrt dma_alloc_coherent. The current pci-dma.c
does, so I think that it would be better to keep the current behavior.


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