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From: Grant Grundler <iod00d@hp.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	Matthew Wilcox <matthew@wil.cx>,
	linux-kernel@vger.kernel.org, discuss@x86-64.org,
	linux-ia64@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz,
	ak@suse.de, "Mallick, Asit K" <asit.k.mallick@intel.com>,
	gregkh@suse.de
Subject: Re: [patch 2.6.14-rc2 0/5] swiotlb maintenance and x86_64 dma_sync_single_range_for_{cpu,device}
Date: Mon, 26 Sep 2005 15:46:03 -0700	[thread overview]
Message-ID: <20050926224603.GD16113@esmail.cup.hp.com> (raw)
In-Reply-To: <B8E391BBE9FE384DAA4C5C003888BE6F047E9021@scsmsx401.amr.corp.intel.com>

On Mon, Sep 26, 2005 at 03:08:23PM -0700, Luck, Tony wrote:
> Historically swiotlb.c was written with just PCI in mind (hence
> all the comments ("... implement the PCI DMA API",  "The PCI address
> to use is returned", "teardown the PCI dma mapping") and a few
> error messages ("PCI-DMA: Out of SW-IOMMU space ...", "PCI-DMA: Memory
> would be corrupted", "PCI-DMA: Random memory would be DMAed").
> Perhaps back then the only options were PCI and ISA????

Yes. The DMA interface davem/et al introduce in linux-2.4 only
supported "PCI-Like" busses. Ie the API required struct pci_dev.

> Matthew is probably technically right in that this is a more
> generic interface ... but is it actually being used for anything
> other than PCI?  Will it ever be so used?

Besides 32-bit PCI devices, I expect legacy 24-bit E/ISA DMA will
need it.  Is ISA ~= PCI? I never got a clear answer on that.
I'm inclined to say it's not.

But since swiotlb complies with DMA-API interface and is not related
to any particular type of bus, I'd rather it go into lib/ instead of
drivers/pci.

hth,
grant

  reply	other threads:[~2005-09-26 22:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-26 22:08 [patch 2.6.14-rc2 0/5] swiotlb maintenance and x86_64 dma_sync_single_range_for_{cpu,device} Luck, Tony
2005-09-26 22:46 ` Grant Grundler [this message]
2005-09-27  0:14   ` John W. Linville
2005-09-27  2:47     ` Tony Luck
2005-09-28 21:50       ` [patch 2.6.14-rc2 0/6] " John W. Linville
2005-09-28 21:50         ` [patch 2.6.14-rc2 1/6] swiotlb: move from arch/ia64/lib/ to lib/ John W. Linville
2005-09-28 21:50           ` [patch 2.6.14-rc2 2/6] swiotlb: cleanup some code duplication cruft John W. Linville
2005-09-28 21:50             ` [patch 2.6.14-rc2 3/6] swiotlb: support syncing sub-ranges of mappings John W. Linville
2005-09-28 21:50               ` [patch 2.6.14-rc2 4/6] swiotlb: support syncing DMA_BIDIRECTIONAL mappings John W. Linville
2005-09-28 21:50                 ` [patch 2.6.14-rc2 5/6] swiotlb: file header comments John W. Linville
2005-09-28 21:50                   ` [patch 2.6.14-rc2 6/6] x86_64: implement dma_sync_single_range_for_{cpu,device} John W. Linville
2005-09-29 22:42         ` [patch 2.6.14-rc2 0/6] swiotlb maintenance and x86_64 dma_sync_single_range_for_{cpu,device} Luck, Tony
  -- strict thread matches above, loose matches on Subject: below --
2005-09-23 18:27 [patch 2.6.13 " Luck, Tony
2005-09-26 21:01 ` [patch 2.6.14-rc2 0/5] " John W. Linville
2005-09-26 21:33   ` Matthew Wilcox
2005-09-26 21:54     ` John W. Linville

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