From: Christoph Hellwig <hch@lst.de>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-samsung-soc@vger.kernel.org,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Sylwester Nawrocki <snawrocki@kernel.org>,
linux-kernel@vger.kernel.org,
Krzysztof Kozlowski <krzk@kernel.org>,
Linux IOMMU <iommu@lists.linux-foundation.org>,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>,
linux-media@vger.kernel.org
Subject: Re: [PATCH 1/8] dma-mapping: add DMA_ATTR_LOW_ADDRESS attribute
Date: Fri, 25 Sep 2020 18:20:03 +0200 [thread overview]
Message-ID: <20200925162003.GA18879@lst.de> (raw)
In-Reply-To: <20200925141218.13550-2-m.szyprowski@samsung.com>
> #define DMA_ATTR_PRIVILEGED (1UL << 9)
> +/*
> + * DMA_ATTR_LOW_ADDRESS: used to indicate that the buffer should be allocated
> + * at the lowest possible DMA address, usually just at the beginning of the
> + * DMA/IOVA address space ('first-fit' allocation algorithm).
> + */
> +#define DMA_ATTR_LOW_ADDRESS (1UL << 10)
I think we need better comments explaining that this is best effort
and only applies to DMA API implementations that actually have an
allocatable IOVA space.
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next prev parent reply other threads:[~2020-09-25 16:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200925141230eucas1p1b4bb8a7e17a887c6ca6a7b8caa7cf9c7@eucas1p1.samsung.com>
2020-09-25 14:12 ` [PATCH 0/8] IOMMU-DMA - support old allocation algorithm used on ARM Marek Szyprowski
2020-09-25 14:12 ` [PATCH 1/8] dma-mapping: add DMA_ATTR_LOW_ADDRESS attribute Marek Szyprowski
2020-09-25 16:20 ` Christoph Hellwig [this message]
2020-09-25 14:12 ` [PATCH 2/8] iommu: iova: properly handle 0 as a valid IOVA address Marek Szyprowski
2020-09-25 14:12 ` [PATCH 3/8] iommu: iova: add support for 'first-fit' algorithm Marek Szyprowski
2020-09-25 14:12 ` [PATCH 4/8] iommu: dma-iommu: refactor iommu_dma_alloc_iova() Marek Szyprowski
2020-09-25 14:12 ` [PATCH 5/8] iommu: dma-iommu: add support for DMA_ATTR_LOW_ADDRESS Marek Szyprowski
2020-09-25 14:12 ` [PATCH 6/8] media: platform: exynos4-is: remove all references to physicall addresses Marek Szyprowski
2020-09-25 14:12 ` [PATCH 7/8] media: platform: exynos4-is: use DMA_ATTR_LOW_ADDRESS Marek Szyprowski
2020-09-25 14:12 ` [PATCH 8/8] media: platform: s5p-mfc: " Marek Szyprowski
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