[alsa-devel] [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap

Lars-Peter Clausen lars at metafoo.de
Thu Jun 28 14:30:26 CEST 2012

On 06/28/2012 02:18 PM, Mark Brown wrote:
> On Thu, Jun 28, 2012 at 02:15:38PM +0200, Takashi Iwai wrote:
>> Lars-Peter Clausen wrote:
>>> 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.
> Oh, dear - this means we don't actually have a generic API at all.  Is
> there any effort being made to make this generally available?

Yes there is, and in fact in next/master there is generic
dma_mmap_writecombine. I'm not quite sure how it behaves on non ARM archs
though. But in theory it should fallback to a normal coherent mapping. Marek
did a lot of work on this, I've put him on Cc.

- Lars

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