Messages in this thread | | | Date | Thu, 28 Jun 2012 14:15:38 +0200 | From | Takashi Iwai <> | Subject | Re: [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap |
| |
At Thu, 28 Jun 2012 13:09:36 +0200, Lars-Peter Clausen wrote: > > 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.
Agreed.
Also, it must be portable. So far, only ARM has dma_mmap_writecombine(), thus the build on other arch would fail as is.
thanks,
Takashi
> > - 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); >
| |