linux-kernel - Re: [net-next PATCH RFC 05/26] arch/avr32: Add option to skip sync on DMA map

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Date:   Mon, 24 Oct 2016 20:27:40 +0200
From:   Hans-Christian Noren Egtvedt <egtvedt@...fundet.no>
To:     Alexander Duyck <alexander.h.duyck@...el.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, brouer@...hat.com,
        Haavard Skinnemoen <hskinnemoen@...il.com>, davem@...emloft.net
Subject: Re: [net-next PATCH RFC 05/26] arch/avr32: Add option to skip sync
 on DMA map

Around Mon 24 Oct 2016 08:04:53 -0400 or thereabout, Alexander Duyck wrote:
> The use of DMA_ATTR_SKIP_CPU_SYNC was not consistent across all of the DMA
> APIs in the arch/arm folder.  This change is meant to correct that so that
> we get consistent behavior.

Looks good (-:

> Cc: Haavard Skinnemoen <hskinnemoen@...il.com>
> Cc: Hans-Christian Egtvedt <egtvedt@...fundet.no>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>

Acked-by: Hans-Christian Noren Egtvedt <egtvedt@...fundet.no>

> ---
>  arch/avr32/mm/dma-coherent.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/avr32/mm/dma-coherent.c b/arch/avr32/mm/dma-coherent.c
> index 58610d0..54534e5 100644
> --- a/arch/avr32/mm/dma-coherent.c
> +++ b/arch/avr32/mm/dma-coherent.c
> @@ -146,7 +146,8 @@ static dma_addr_t avr32_dma_map_page(struct device *dev, struct page *page,
>  {
>  	void *cpu_addr = page_address(page) + offset;
>  
> -	dma_cache_sync(dev, cpu_addr, size, direction);
> +	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
> +		dma_cache_sync(dev, cpu_addr, size, direction);
>  	return virt_to_bus(cpu_addr);
>  }
>  
> @@ -162,6 +163,10 @@ static int avr32_dma_map_sg(struct device *dev, struct scatterlist *sglist,
>  
>  		sg->dma_address = page_to_bus(sg_page(sg)) + sg->offset;
>  		virt = sg_virt(sg);
> +
> +		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
> +			continue;
> +
>  		dma_cache_sync(dev, virt, sg->length, direction);
>  	}
>  
-- 
mvh
Hans-Christian Noren Egtvedt