From: Eugene Surovegin <ebs@ebshome.net>
To: John Whitney <jwhitney-linuxppc@sands-edge.com>
Cc: linuxppc-dev@lists.linuxppc.org,
Matt Porter <mporter@kernel.crashing.org>
Subject: Re: Problems with dma_alloc_coherent()
Date: Thu, 1 Apr 2004 10:40:04 -0800 [thread overview]
Message-ID: <20040401184004.GA3786@gate.ebshome.net> (raw)
In-Reply-To: <1A3C4ACE-840B-11D8-9FF0-000A95A07384@sands-edge.com>
On Thu, Apr 01, 2004 at 01:33:42PM -0500, John Whitney wrote:
> Yes, but both pci_alloc_consistent() and dma_alloc_coherent() return
> physical addresses made with virt_to_bus() (at least they do in the
> PowerPC tree). This routine specifically adds the PCI-bus view of the
> address space to the physical address produced. I don't understand why
> two different APIs are needed, if they both do the same thing.
They do the same thing _now_, because it's a _new_ API. This _may_ change in
future.
DMA API is needed, because generic code uses it, most archs have default generic
implementation which use PCI DMA API and I don't see _any_ problems with that.
Some archs may have _different_ implementations which DON'T use PCI DMA API.
>
> This means that the address produced by pci_alloc_... and dma_alloc_...
> are incorrect for a device like a direct memory-mapped encryption chip,
> or in my case a northbridge DMA controller.
It depends, on all systems I use PCI view == phys address, so it'll work.
Eugene
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-04-01 18:40 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-01 15:59 Problems with dma_alloc_coherent() John Whitney
2004-04-01 16:30 ` John Whitney
2004-04-01 16:51 ` Dan Malek
2004-04-01 17:01 ` Tom Rini
2004-04-01 17:05 ` Matt Porter
2004-04-01 17:51 ` John Whitney
2004-04-01 18:16 ` Matt Porter
2004-04-01 18:19 ` Eugene Surovegin
2004-04-01 18:33 ` Eugene Surovegin
2004-04-01 18:33 ` John Whitney
2004-04-01 18:40 ` Eugene Surovegin [this message]
2004-04-01 18:48 ` John Whitney
2004-04-01 18:55 ` Dan Malek
2004-04-01 18:59 ` Eugene Surovegin
2004-04-01 19:10 ` John Whitney
2004-04-01 19:17 ` Eugene Surovegin
2004-04-01 19:35 ` John Whitney
2004-04-02 1:22 ` Benjamin Herrenschmidt
2004-04-01 20:52 ` Michael R. Zucca
2004-04-01 22:00 ` Eugene Surovegin
2004-04-01 22:39 ` Michael R. Zucca
2004-04-02 16:50 ` John Whitney
2004-04-02 18:50 ` Michael R. Zucca
2004-04-02 19:27 ` John Whitney
2004-04-02 20:20 ` Michael R. Zucca
2004-04-02 21:01 ` John Whitney
2004-04-03 7:54 ` Adrian Cox
2004-04-03 12:43 ` John Whitney
2004-04-05 9:05 ` Adrian Cox
2004-04-03 17:33 ` Brad Boyer
2004-04-03 23:17 ` Paul Mackerras
2004-04-04 8:15 ` Adrian Cox
2004-04-02 22:54 ` Paul Mackerras
2004-04-03 7:33 ` Adrian Cox
2004-04-04 22:56 ` Benjamin Herrenschmidt
2004-04-02 5:45 ` Christoph Hellwig
2004-04-01 20:49 ` Matt Porter
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