linux-kernel - Re: [PATCH 2/2] x86: gart alloc_coherent does virtual mapppings only when necessary

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Message-ID: <20080911141613.GL24392@amd.com>
Date:	Thu, 11 Sep 2008 16:16:14 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
CC:	mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: gart alloc_coherent does virtual mapppings only when necessary

Looks good to me.

On Thu, Sep 11, 2008 at 11:08:48PM +0900, FUJITA Tomonori wrote:
> gart alloc_coherent need to do virtual mapppings only when an
> allocated buffer is not DMA-capable for a device.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> Cc: Joerg Roedel <joerg.roedel@....com>

Acked-by: Joerg Roedel <joerg.roedel@....com>

> ---
>  arch/x86/kernel/pci-gart_64.c |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
> index 1b0c412..47abe43 100644
> --- a/arch/x86/kernel/pci-gart_64.c
> +++ b/arch/x86/kernel/pci-gart_64.c
> @@ -488,15 +488,23 @@ 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);
>  
>  	vaddr = (void *)__get_free_pages(flag | __GFP_ZERO, get_order(size));
>  	if (!vaddr)
>  		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;
>  
> -	*dma_addr = dma_map_area(dev, __pa(vaddr), size, DMA_BIDIRECTIONAL,
> +	*dma_addr = dma_map_area(dev, paddr, size, DMA_BIDIRECTIONAL,
>  				 align_mask);
>  	flush_gart();
>  
> -- 
> 1.5.4.2
> 
> 

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