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From: Christoph Hellwig <hch@infradead.org>
To: "Christian König" <christian.koenig@amd.com>
Cc: linaro-mm-sig@lists.linaro.org, David1.Zhou@amd.com,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	Christoph Hellwig <hch@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Logan Gunthorpe <logang@deltatee.com>,
	linux-media@vger.kernel.org
Subject: Re: [Intel-gfx] [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function
Date: Mon, 16 Mar 2020 02:52:13 -0700	[thread overview]
Message-ID: <20200316095213.GA29212@infradead.org> (raw)
In-Reply-To: <eb567569-426a-0845-b443-a20155897705@amd.com>

On Mon, Mar 16, 2020 at 10:41:42AM +0100, Christian König wrote:
> Well I would prefer if the drivers can somehow express their requirements
> and get IOVA structures already in the form they need.
> 
> Converting the IOVA data from one form to another is sometimes quite costly.
> Especially when it is only temporarily needed.

We basically have two ways to generate the IOVA:

  - a linear translation for the direct mapping case or some dumb IOMMU
    drivers - in that case case there is a 1:1 mapping between input
    segments and output segments in DMA mapping
  - a non-trivial IOMMU where all aligned segments are merged into
    a single IOVA range

So I don't really see how the dma layer could help much with any
limitation beyond existing max size and dma boundary ones.
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  reply	other threads:[~2020-03-16 14:17 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 13:51 [Intel-gfx] P2P for DMA-buf Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function Christian König
2020-03-11 15:28   ` Christoph Hellwig
2020-03-12 10:14     ` Christian König
2020-03-12 10:19       ` Christoph Hellwig
2020-03-12 10:31         ` Christian König
2020-03-12 10:47           ` Christoph Hellwig
2020-03-12 11:02             ` Christian König
     [not found]             ` <20200312141928.GK31668@ziepe.ca>
2020-03-12 15:39               ` Christian König
2020-03-12 16:13               ` Logan Gunthorpe
2020-03-13 11:21               ` Christoph Hellwig
2020-03-13 13:33                 ` Christian König
     [not found]                 ` <20200313121742.GZ31668@ziepe.ca>
2020-03-16  8:56                   ` Christoph Hellwig
2020-03-16  9:41                     ` Christian König
2020-03-16  9:52                       ` Christoph Hellwig [this message]
2020-03-11 13:51 ` [Intel-gfx] [PATCH 2/6] dma-buf: add peer2peer flag Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 3/6] drm/amdgpu: note that we can handle peer2peer DMA-buf Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 4/6] drm/amdgpu: add checks if DMA-buf P2P is supported Christian König
     [not found]   ` <20200311140415.GB31668@ziepe.ca>
2020-03-11 14:33     ` Christian König
     [not found]       ` <20200311143835.GD31668@ziepe.ca>
2020-03-11 14:43         ` Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 5/6] drm/amdgpu: add support for exporting VRAM using DMA-buf v2 Christian König
2020-03-11 15:08   ` Alex Deucher
2020-03-11 13:51 ` [Intel-gfx] [PATCH 6/6] drm/amdgpu: improve amdgpu_gem_info debugfs file Christian König
2020-03-11 18:09 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/6] lib/scatterlist: add sg_set_dma_addr() function Patchwork
2020-03-11 18:34 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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