Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource

From	Christoph Hellwig <hch@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource
Date	2016-03-15 09:30 +0100
Message-ID	<rcSwx-7WK-1@gated-at.bofh.it> (permalink)
References	(2 earlier) <rakpk-6eV-17@gated-at.bofh.it> <rbbjZ-119-15@gated-at.bofh.it> <rbp3z-27t-5@gated-at.bofh.it> <rbtgS-5hR-19@gated-at.bofh.it> <rbuPE-6r7-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Mar 11, 2016 at 01:58:46PM +0100, Niklas S?derlund wrote:
> Without an IOMMU this is easy since the phys_addr_t and dma_addr_t are 
> the same and no special care is needed. However if you have a IOMMU you 
> need to map the DMA slave phys_addr_t to a dma_addr_t using something 
> like this. Is it not very similar to dma_map_single() where one maps 
> processor virtual memory (instead if MMIO) so that it can be used with 
> DMA slaves?

It's similar, but I don't think this actually works as a general case
as there are quite a few places that expect to be able to have a
struct page for a physical address.  We'd at least need a very careful
audit for that case.

Thread

[PATCH v5 0/9] dmaengine: rcar-dmac: add iommu support for slave transfers Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100
  [PATCH v5 4/9] arm: dma-mapping: add {map,unmap}_resource for iommu ops Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100
  [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100
    Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Christoph Hellwig <hch@infradead.org> - 2016-03-08 08:40 +0100
      Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource "Niklas S??derlund" <niklas.soderlund@ragnatech.se> - 2016-03-10 17:10 +0100
        Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Vinod Koul <vinod.koul@intel.com> - 2016-03-11 07:20 +0100
        Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Dan Williams <dan.j.williams@intel.com> - 2016-03-11 07:50 +0100
          Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Christoph Hellwig <hch@infradead.org> - 2016-03-11 12:20 +0100
            Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Niklas Söderlund   <niklas.soderlund@ragnatech.se> - 2016-03-11 14:00 +0100
              Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Christoph Hellwig <hch@infradead.org> - 2016-03-15 09:30 +0100
          Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Robin Murphy <robin.murphy@arm.com> - 2016-03-11 14:50 +0100
            Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource Dan Williams <dan.j.williams@intel.com> - 2016-03-11 19:00 +0100
  [PATCH v5 9/9] ARM: dts: r8a7791: add iommus to dmac0 and dmac1 Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100
  [PATCH v5 1/9] iommu: Add MMIO mapping type Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100
  [PATCH v5 6/9] dmaengine: rcar-dmac: group slave configuration Niklas Söderlund   <niklas.soderlund+renesas@ragnatech.se> - 2016-03-08 03:50 +0100

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