Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1360259

Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with dma_map_single

Show all headers | View raw

On Thu, Mar 17, 2016 at 07:17:24PM -0400, okaya@codeaurora.org wrote:
> What is the correct way? I don't want to write engine->sram_dma = sram

Well, what the driver _is_ wanting to do is to go from a CPU physical
address to a device DMA address.  phys_to_dma() looks like the correct
thing there to me, but I guess that's just an offset and doesn't take
account of any IOMMU that may be in the way.

If you have an IOMMU, then the whole phys_to_dma() thing is a total
failure as it only does a linear translation, and there are no
interfaces in the kernel to take account of an IOMMU in the way.  So,
it needs something designed for the job, implemented and discussed by
the normal methods of proposing a new cross-arch interface for drivers
to use.

What I'm certain of, though, is that the change proposed in this patch
will break current users of this driver: virt_to_page() on an address
returned by ioremap() is completely undefined, and will result in
either a kernel oops, or if not poking at memory which isn't a struct
page, ultimately resulting in something that isn't SRAM being pointed
to by "engine->sram_dma".

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with dma_map_single Sinan Kaya <okaya@codeaurora.org> - 2016-03-17 23:10 +0100
  [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Sinan Kaya <okaya@codeaurora.org> - 2016-03-17 23:10 +0100
    Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Robin Murphy <robin.murphy@arm.com> - 2016-03-18 13:20 +0100
      Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Sinan Kaya <okaya@codeaurora.org> - 2016-03-18 16:10 +0100
        Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Konrad Rzeszutek Wilk <konrad@kernel.org> - 2016-03-28 20:30 +0200
          Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma  functions Stefano Stabellini <sstabellini@kernel.org> - 2016-03-29 14:50 +0200
            Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Sinan Kaya <okaya@codeaurora.org> - 2016-03-29 15:00 +0200
          Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions Arnd Bergmann <arnd@arndb.de> - 2016-03-29 21:40 +0200
  [PATCH 3/3] dma-mapping: move swiotlb dma-phys functions to common header Sinan Kaya <okaya@codeaurora.org> - 2016-03-17 23:10 +0100
    Re: [PATCH 3/3] dma-mapping: move swiotlb dma-phys functions to  common header Robin Murphy <robin.murphy@arm.com> - 2016-03-18 12:40 +0100
      Re: [PATCH 3/3] dma-mapping: move swiotlb dma-phys functions to  common header Sinan Kaya <okaya@codeaurora.org> - 2016-03-18 15:00 +0100
  Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-03-18 00:00 +0100
    Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single okaya@codeaurora.org - 2016-03-18 00:20 +0100
      Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-03-18 01:00 +0100
        Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-18 10:40 +0100
          Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Robin Murphy <robin.murphy@arm.com> - 2016-03-18 12:30 +0100
            Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-18 12:40 +0100
            Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Sinan Kaya <okaya@codeaurora.org> - 2016-03-18 15:00 +0100
              Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Sinan Kaya <okaya@codeaurora.org> - 2016-03-18 15:10 +0100
              Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Sinan Kaya <okaya@codeaurora.org> - 2016-03-18 15:30 +0100
              Re: [PATCH 1/3] crypto: marvell/cesa - replace dma_to_phys with  dma_map_single Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-03-18 15:30 +0100

csiph-web