Messages in this thread | | | Date | Thu, 28 Jun 2012 13:09:36 +0200 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap |
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On 06/28/2012 09:01 AM, Laxman Dewangan wrote: > The pcm mmap for the substream dma buffer is done using the > dma_mmap_writecombine(). > Some of the chip sound driver like Spear, Tegra, Davinci, > ep93xx,snd_imx, snd_mxs, NUC900, OMAP, Samsung are doing this > mapping locally. > Add api in the snd dmaengine driver so that different client of > snd dmaengine can use this rather than implementing locally. >
This is not really related to the dmaengine pcm driver. It's more of a coincidence that all upstream drivers which use the dmaengine pcm driver also use write-combined memory. In my opinion it would be better to add this to the ALSA core. Now that there is a generic dma_mmap_writecombine it may make sense to integrate this with snd_pcm_lib_default_mmap.
- Lars
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> > --- > include/sound/dmaengine_pcm.h | 2 ++ > sound/soc/soc-dmaengine-pcm.c | 17 +++++++++++++++++ > 2 files changed, 19 insertions(+), 0 deletions(-) > > diff --git a/include/sound/dmaengine_pcm.h b/include/sound/dmaengine_pcm.h > index b877334..15c0d3c 100644 > --- a/include/sound/dmaengine_pcm.h > +++ b/include/sound/dmaengine_pcm.h > @@ -47,4 +47,6 @@ int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream); > > struct dma_chan *snd_dmaengine_pcm_get_chan(struct snd_pcm_substream *substream); > > +int snd_dmaengine_pcm_mmap_writecombine(struct snd_pcm_substream *substream, > + struct vm_area_struct *vma); > #endif > diff --git a/sound/soc/soc-dmaengine-pcm.c b/sound/soc/soc-dmaengine-pcm.c > index 5df529e..6535eb3 100644 > --- a/sound/soc/soc-dmaengine-pcm.c > +++ b/sound/soc/soc-dmaengine-pcm.c > @@ -21,6 +21,7 @@ > #include <linux/module.h> > #include <linux/init.h> > #include <linux/dmaengine.h> > +#include <linux/dma-mapping.h> > #include <linux/slab.h> > #include <sound/pcm.h> > #include <sound/pcm_params.h> > @@ -313,3 +314,19 @@ int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream) > return 0; > } > EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close); > + > +/** > + * snd_dmaengine_pcm_mmap_writecombine - mmap stream dma buffer using > + * dma_mmap_writecombine(). > + * @substream: PCM substream > + * @vma: VM area. > + */ > +int snd_dmaengine_pcm_mmap_writecombine(struct snd_pcm_substream *substream, > + struct vm_area_struct *vma) > +{ > + struct snd_pcm_runtime *runtime = substream->runtime; > + > + return dma_mmap_writecombine(substream->pcm->card->dev, vma, > + runtime->dma_area, runtime->dma_addr, runtime->dma_bytes); > +} > +EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_mmap_writecombine);
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