Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool

From	Christoph Hellwig <hch@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool
Date	2017-06-20 15:50 +0200
Message-ID	<tUrHz-Q2-9@gated-at.bofh.it> (permalink)
References	<tKBIe-15d-7@gated-at.bofh.it> <tKCkV-1Ap-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, May 24, 2017 at 11:24:29AM +0100, Vladimir Murzin wrote:
> This patch introduces default coherent DMA pool similar to default CMA
> area concept. To keep other users safe code kept under CONFIG_ARM.

I don't see a CONFIG_ARM in the code, although parts of it are added
under CONFIG_OF_RESERVED_MEM.

But overall this code look a bit odd to me.  As far as I can tell
the dma-coherent.c code is for the case where we have a special
piece of coherent memory close to a device.

If you're allocating out of the global allocator the memory should
come from the normal dma_ops ->alloc allocator - and also take
the attrs into account (e.g. for DMA_ATTR_NON_CONSISTENT or
DMA_ATTR_NO_KERNEL_MAPPING requests you don't need coherent memory)

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Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Christoph Hellwig <hch@infradead.org> - 2017-06-20 15:50 +0200
  Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Robin Murphy <robin.murphy@arm.com> - 2017-06-20 16:30 +0200
    Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Christoph Hellwig <hch@infradead.org> - 2017-06-26 11:50 +0200
      Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Vladimir Murzin <vladimir.murzin@arm.com> - 2017-06-26 16:10 +0200
      Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Robin Murphy <robin.murphy@arm.com> - 2017-06-27 16:40 +0200
        Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Christoph Hellwig <hch@infradead.org> - 2017-06-27 17:30 +0200
  Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Vladimir Murzin <vladimir.murzin@arm.com> - 2017-06-22 15:20 +0200
    Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Christoph Hellwig <hch@infradead.org> - 2017-06-26 11:50 +0200

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