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From: Robin Murphy <robin.murphy@arm.com>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	ulf.hansson@linaro.org, hch@lst.de, m.szyprowski@samsung.com,
	joro@8bytes.org, axboe@kernel.dk
Cc: linux-block@vger.kernel.org, wsa+renesas@sang-engineering.com,
	iommu@lists.linux-foundation.org, linux-mmc@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v9 2/5] iommu/dma: Add a new dma_map_ops of get_merge_boundary()
Date: Mon, 19 Aug 2019 13:54:58 +0100
Message-ID: <312d6e38-5143-fb07-1efb-01e60cafa2c9@arm.com> (raw)
In-Reply-To: <1564129876-28261-3-git-send-email-yoshihiro.shimoda.uh@renesas.com>

On 26/07/2019 09:31, Yoshihiro Shimoda wrote:
> This patch adds a new dma_map_ops of get_merge_boundary() to
> expose the DMA merge boundary if the domain type is IOMMU_DOMAIN_DMA.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
> ---
>   drivers/iommu/dma-iommu.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index a7f9c3e..2992ce4 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1085,6 +1085,16 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
>   	return ret;
>   }
>   
> +static unsigned long iommu_dma_get_merge_boundary(struct device *dev)
> +{
> +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +
> +	if (domain->type != IOMMU_DOMAIN_DMA)

Did you actually need this check? In principle, if the default domain is 
not of type IOMMU_DOMAIN_DMA then the device should be assigned 
dma_direct_ops rather than iommu_dma_ops, thus it shouldn't be possible 
to get here. If you did manage to hit a case where the domain type 
didn't match the ops it would be interesting to figure out how.

Robin.

> +		return 0;	/* can't merge */
> +
> +	return (1UL << __ffs(domain->pgsize_bitmap)) - 1;
> +}
> +
>   static const struct dma_map_ops iommu_dma_ops = {
>   	.alloc			= iommu_dma_alloc,
>   	.free			= iommu_dma_free,
> @@ -1100,6 +1110,7 @@ static const struct dma_map_ops iommu_dma_ops = {
>   	.sync_sg_for_device	= iommu_dma_sync_sg_for_device,
>   	.map_resource		= iommu_dma_map_resource,
>   	.unmap_resource		= iommu_dma_unmap_resource,
> +	.get_merge_boundary	= iommu_dma_get_merge_boundary,
>   };
>   
>   /*
> 
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  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-26  8:31 [PATCH v9 0/5] treewide: improve R-Car SDHI performance Yoshihiro Shimoda
2019-07-26  8:31 ` [PATCH v9 1/5] dma: Introduce dma_get_merge_boundary() Yoshihiro Shimoda
2019-07-26  8:31 ` [PATCH v9 2/5] iommu/dma: Add a new dma_map_ops of get_merge_boundary() Yoshihiro Shimoda
2019-08-16 19:48   ` Wolfram Sang
2019-08-19 12:45   ` Joerg Roedel
2019-08-19 12:54   ` Robin Murphy [this message]
2019-08-20  1:42     ` Yoshihiro Shimoda
2019-07-26  8:31 ` [PATCH v9 3/5] block: sort headers on blk-setting.c Yoshihiro Shimoda
2019-08-16 19:50   ` Wolfram Sang
2019-08-19 14:53     ` Jens Axboe
2019-08-20  1:50       ` Yoshihiro Shimoda
2019-08-22  9:35       ` Wolfram Sang
2019-07-26  8:31 ` [PATCH v9 4/5] block: add a helper function to merge the segments Yoshihiro Shimoda
2019-07-26  8:31 ` [PATCH v9 5/5] mmc: queue: Use bigger segments if DMA MAP layer can " Yoshihiro Shimoda
2019-08-15  7:30 ` [PATCH v9 0/5] treewide: improve R-Car SDHI performance Christoph Hellwig

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