From: Matt Porter <mporter@kernel.crashing.org>
To: John Whitney <jwhitney-linuxppc@sands-edge.com>
Cc: linuxppc-dev@lists.linuxppc.org
Subject: Re: Problems with dma_alloc_coherent()
Date: Thu, 1 Apr 2004 10:05:46 -0700 [thread overview]
Message-ID: <20040401100546.A27472@home.com> (raw)
In-Reply-To: <9EB527A2-83F5-11D8-9FF0-000A95A07384@sands-edge.com>; from jwhitney-linuxppc@sands-edge.com on Thu, Apr 01, 2004 at 10:59:56AM -0500
On Thu, Apr 01, 2004 at 10:59:56AM -0500, John Whitney wrote:
> In the process of reworking my Generic DMA core for the 2.6 kernel, I
> noticed that dma_alloc_coherent() returns NULL in all cases on a
> cache-coherent platform. Instead, I think it would be better if this
> routine returned a block of contiguous memory (not cache-inhibited), as
> pci_alloc_consistent() does.
Yeah, that's really broken. The changeover to dma-mapping.h is
incomplete. Tom and I were just talking about this because I
think it exposes a bigger problem. What I originally wanted
was the PCI DMA API defined in terms of the generic DMA API
on ppc32. He just pointed out asm-generic/pci-dma-compat.h that
we can leverage to do that.
> To that end, I am submitting the attached patch which modifies
> dma_alloc_coherent() and dma_free_coherent() to do just this for
> cache-coherent platforms.
Your patch fixes the problem but exposes the bigger issue that we
are starting to duplicate code since on ppc32 PCI DMA API and DMA
API are handled the same on the backend.
In the meantime (I think Tom volunteered to clean this up!), I think
this needs to go in so we are at least functional.
-Matt
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-04-01 17:05 UTC|newest]
Thread overview: 36+ 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 [this message]
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
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
2004-04-01 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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