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Re: [PATCH 4/5] ALSA: pcm - fix page conversion on non-coherent PPC arch

To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 4/5] ALSA: pcm - fix page conversion on non-coherent PPC arch
From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 27 Nov 2009 10:18:24 +0100
Cc: alsa-devel@alsa-project.org, Ralf Baechle <ralf@linux-mips.org>, Wu Zhangjin <wuzhangjin@gmail.com>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, linux-mips@linux-mips.org, Kumar Gala <galak@gate.crashing.org>, Becky Bruce <beckyb@kernel.crashing.org>
In-reply-to: <1259268704.18084.4.camel@pasglop>
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At Fri, 27 Nov 2009 07:51:44 +1100,
Benjamin Herrenschmidt wrote:
> 
> On Thu, 2009-11-26 at 16:13 +0100, Takashi Iwai wrote:
> > The non-cohernet PPC arch doesn't give the correct address by a simple
> > virt_to_page() for pages allocated via dma_alloc_coherent().
> > This patch adds a hack to fix the conversion similarly like MIPS.
> > 
> > Note that this doesn't fix perfectly: the pages should be marked with
> > proper pgprot value.  This will be done in a future implementation like
> > the conversion to dma_mmap_coherent().
> > 
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> 
> This will not work with swiotlb, but then, I don't think we have -yet-
> to deal with a platform that does both swiotlb and isn't DMA
> coherent :-)
> 
> Of course, the conversion to dma_mmap_coherent will makes things better
> though we really will want to push that function into the dma ops.
> 
> So it's hackish but for now its an
> 
> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Thanks, I added your ack to the GIT commit.


Takashi

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