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Re: [PATCH 3/5] ALSA: pcm - fix page conversion on non-coherent MIPS arc

To: wuzhangjin@gmail.com
Subject: Re: [PATCH 3/5] ALSA: pcm - fix page conversion on non-coherent MIPS arch
From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 27 Nov 2009 10:26:15 +0100
Cc: alsa-devel@alsa-project.org, Ralf Baechle <ralf@linux-mips.org>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, linux-mips@linux-mips.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Kumar Gala <galak@gate.crashing.org>, Becky Bruce <beckyb@kernel.crashing.org>
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At Fri, 27 Nov 2009 11:52:58 +0800,
Wu Zhangjin wrote:
> 
> On Thu, 2009-11-26 at 16:13 +0100, Takashi Iwai wrote:
> > The non-coherent MIPS arch doesn't give the correct address by a simple
> > virt_to_page() for pages allocated via dma_alloc_coherent().
> > 
> > Original patch by Wu Zhangjin <wuzj@lemote.com>.  A proper check of the
> > buffer allocation type was added to avoid the wrong conversion.
> > 
> > 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>
> > ---
> >  sound/core/pcm_native.c |    4 ++++
> >  1 files changed, 4 insertions(+), 0 deletions(-)
> > 
> > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> > index c906be2..e48c5f6 100644
> > --- a/sound/core/pcm_native.c
> > +++ b/sound/core/pcm_native.c
> > @@ -3066,6 +3066,10 @@ static inline struct page *
> >  snd_pcm_default_page_ops(struct snd_pcm_substream *substream, unsigned 
> > long ofs)
> >  {
> >     void *vaddr = substream->runtime->dma_area + ofs;
> > +#if defined(CONFIG_MIPS) && defined(CONFIG_DMA_NONCOHERENT)
> > +   if (substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
> > +           return virt_to_page(CAC_ADDR(vaddr));
> > +#endif
> >     return virt_to_page(vaddr);
> >  }
> 
> Works well on Loongson family machines, thanks!

Thanks for checking!


Takashi

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