From: m.szyprowski@samsung•com (Marek Szyprowski)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC 0/3] How to pass IOMMU map attr via DMA API?
Date: Fri, 21 Jun 2013 09:17:59 +0200 [thread overview]
Message-ID: <51C3FE27.5070702@samsung.com> (raw)
In-Reply-To: <1371707384-30037-1-git-send-email-hdoyu@nvidia.com>
Hello,
On 6/20/2013 7:49 AM, Hiroshi Doyu wrote:
> In Tegra SoC, IOMMU can set some mapping attribute for each page, for
> exmaple, READable, and WRITEable. We'd like to use this feature
> *newly* for robustness, where read-only pages can be protected from
> being overwritten by wrong operation. We have been using IOMMU via DMA
> mapping API(ARM). DMA mapping API currently doesn't use "prot"
> parameter when calling IOMMU API. So this series tries to pass "struct
> dma_attrs *attrs" via "int prot" in IOMMU API. I'm not so sure if this
> implementation is right or not because:
>
> - Casting (struct dma_attrs *) to (int) in DMA API doesn't look nice.
> - IOMMU layer needs to cast (int) back to (struct dma_attrs *) again,
> which can be considered as violation of layers.
>
> If you have any implementations/suggestions, it would be really helpful.
>
> This series isn't applied cleanly but this is posted to request for
> comments.
Using DMA attributes for this seems to be a bad idea. The dma direction
parameter is much more appropriate. Will Deacon recently posted a patch
which does it right, see:
https://git.linaro.org/gitweb?p=people/mszyprowski/linux-dma-mapping.git;a=commit;h=8fc3749bd31d139db58f874e093255fe62505968
> Hiroshi Doyu (3):
> common: DMA-mapping: add DMA_ATTR_READ_ONLY attribute
> ARM: dma-mapping: Pass DMA attrs as IOMMU prot
> iommu/tegra: smmu: Support read-only mapping
>
> arch/arm/mm/dma-mapping.c | 34 +++++++++++++++++++++-------------
> drivers/iommu/tegra-smmu.c | 41 +++++++++++++++++++++++++++++------------
> include/linux/dma-attrs.h | 1 +
> 3 files changed, 51 insertions(+), 25 deletions(-)
>
Best regards
--
Marek Szyprowski
Samsung R&D Institute Poland
next prev parent reply other threads:[~2013-06-21 7:17 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 5:49 [RFC 0/3] How to pass IOMMU map attr via DMA API? Hiroshi Doyu
[not found] ` <1371707384-30037-4-git-send-email-hdoyu@nvidia.com>
2013-06-20 6:50 ` [Linaro-mm-sig] [RFC 3/3] iommu/tegra: smmu: Support read-only mapping Kyungmin Park
2013-06-20 7:27 ` Hiroshi Doyu
[not found] ` <1371707384-30037-3-git-send-email-hdoyu@nvidia.com>
2013-06-20 8:07 ` [Linaro-mm-sig] [RFC 2/3] ARM: dma-mapping: Pass DMA attrs as IOMMU prot Nishanth Peethambaran
2013-06-20 8:24 ` Hiroshi Doyu
2013-06-20 8:55 ` Nishanth Peethambaran
2013-06-20 9:54 ` Hiroshi Doyu
2013-06-20 10:13 ` Arnd Bergmann
2013-06-20 10:34 ` Hiroshi Doyu
2013-06-20 10:57 ` Arnd Bergmann
2013-06-20 12:49 ` Nishanth Peethambaran
2013-06-20 9:31 ` [RFC 0/3] How to pass IOMMU map attr via DMA API? Will Deacon
2013-06-20 9:59 ` Hiroshi Doyu
2013-06-20 10:11 ` Catalin Marinas
2013-06-20 11:00 ` Hiroshi Doyu
2013-06-20 10:12 ` Will Deacon
2013-06-21 7:17 ` Marek Szyprowski [this message]
2013-06-21 16:03 ` Joerg Roedel
2013-06-24 5:17 ` Hiroshi Doyu
2013-06-24 7:21 ` Joerg Roedel
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