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From: James Hogan <jhogan@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-mips@linux-mips.org, sstabellini@kernel.org,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	linux-pci@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org,
	iommu@lists.linux-foundation.org, sparclinux@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 11/13] mips, unicore32: swiotlb doesn't need sg->dma_length
Date: Thu, 3 May 2018 07:47:32 +0100	[thread overview]
Message-ID: <20180503064731.GA3971@jamesdev> (raw)
In-Reply-To: <20180503035643.GA9781@lst.de>


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On Thu, May 03, 2018 at 05:56:43AM +0200, Christoph Hellwig wrote:
> On Wed, May 02, 2018 at 11:20:18PM +0100, James Hogan wrote:
> > On Wed, Apr 25, 2018 at 07:15:37AM +0200, Christoph Hellwig wrote:
> > > Only mips and unicore32 select CONFIG_NEED_SG_DMA_LENGTH when building
> > > swiotlb.  swiotlb itself never merges segements and doesn't accesses the
> > > dma_length field directly, so drop the dependency.
> > 
> > Is that at odds with Documentation/DMA-API-HOWTO.txt, which seems to
> > suggest arch ports should enable it for IOMMUs?
> 
> swiotlb isn't really an iommu..  That being said iommus don't have to
> merge segments either if they don't want to, and we have various
> implementations that don't.  The whole dma api documentation needs
> a major overhaul, including merging the various files and dropping a lot
> of dead wood.  It has been on my todo list for a while, with an inner
> hope that someone else would do it before me.

Okay, for MIPS:
Acked-by: James Hogan <jhogan@kernel.org>

Cheers
James

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  reply	other threads:[~2018-05-03  6:47 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-25  5:15 centralize SWIOTLB config symbol and misc other cleanups V3 Christoph Hellwig
2018-04-25  5:15 ` [PATCH 01/13] iommu-common: move to arch/sparc Christoph Hellwig
2018-04-25 14:58   ` David Miller
2018-04-25  5:15 ` [PATCH 02/13] iommu-helper: unexport iommu_area_alloc Christoph Hellwig
2018-04-25  5:15 ` [PATCH 03/13] iommu-helper: mark iommu_is_span_boundary as inline Christoph Hellwig
2018-04-25  5:15 ` [PATCH 04/13] iommu-helper: move the IOMMU_HELPER config symbol to lib/ Christoph Hellwig
2018-04-25  5:15 ` [PATCH 05/13] scatterlist: move the NEED_SG_DMA_LENGTH config symbol to lib/Kconfig Christoph Hellwig
2018-04-25  5:15 ` [PATCH 06/13] dma-mapping: move the NEED_DMA_MAP_STATE " Christoph Hellwig
2018-04-25  5:15 ` [PATCH 07/13] arch: remove the ARCH_PHYS_ADDR_T_64BIT config symbol Christoph Hellwig
2018-05-02 20:11   ` James Hogan
2018-04-25  5:15 ` [PATCH 08/13] arch: define the ARCH_DMA_ADDR_T_64BIT config symbol in lib/Kconfig Christoph Hellwig
2018-05-02 22:09   ` James Hogan
2018-04-25  5:15 ` [PATCH 09/13] PCI: remove CONFIG_PCI_BUS_ADDR_T_64BIT Christoph Hellwig
2018-04-25  5:15 ` [PATCH 10/13] arm: don't build swiotlb by default Christoph Hellwig
2018-04-25  5:15 ` [PATCH 11/13] mips,unicore32: swiotlb doesn't need sg->dma_length Christoph Hellwig
2018-05-02 22:20   ` [PATCH 11/13] mips, unicore32: " James Hogan
2018-05-03  3:56     ` [PATCH 11/13] mips,unicore32: " Christoph Hellwig
2018-05-03  6:47       ` James Hogan [this message]
2018-04-25  5:15 ` [PATCH 12/13] swiotlb: move the SWIOTLB config symbol to lib/Kconfig Christoph Hellwig
2018-04-25  5:15 ` [PATCH 13/13] swiotlb: remove the CONFIG_DMA_DIRECT_OPS ifdefs Christoph Hellwig
2018-05-02 12:46 ` centralize SWIOTLB config symbol and misc other cleanups V3 Christoph Hellwig
2018-05-09  5:03   ` Christoph Hellwig

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