Messages in this thread | | | Date | Thu, 28 Jun 2012 16:10:45 +0200 | From | Takashi Iwai <> | Subject | Re: [alsa-devel] [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap |
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At Thu, 28 Jun 2012 19:30:57 +0530, Laxman Dewangan wrote: > > On Thursday 28 June 2012 07:21 PM, Takashi Iwai wrote: > > At Thu, 28 Jun 2012 19:06:07 +0530, > > Laxman Dewangan wrote: > > > >>>> Then how about this? > >>>> create new file and header for snd-pcm-writecombine-buffer.c/.h and put > >>>> this in sound/core. > >>>> Select this file compilation through config SND_PCM_WRITECOMBINE_BUFFER > >>>> which will be select this config through sound/soc/xxx/Kconfig if they > >>>> want to use. > >>>> This will provide three apis: new, free and mmap. > >>> Way too much hustles than necessary... > >> Ooh no. :-( I had taken the idea from snd_dmaengine_pcm driver. > >> Bit I like to hear simple way which solves the purpose. > > As Lars suggested, a simple ifdef should suffice for now. > > With the upcoming generic dma_mmap_writecombine() stuff, it'd be even > > simpler in future. > > > > But, still we need to be careful about this. As mentioned, there is > > no flag to know the possibility of writecombine mmap beforehand. > > It'd be nice if we have either a compile-time or a run-time flag / > > function to check that. Then the driver can also expose the mmap > > capability to user-space depending on the flag. > > Yaah, this seems really simple. Thanks for suggestion. > If I understand it fully, the new apis will be declare in sound/pcm.h, > implement it in pcm_native.c and use the config variable > CONFIG_SND_PCM_WRITECOMBINE_BUFFER for ifdef.
Or this could be simply ifdef CONFIG_ARM. Since this ifdef will be unnecessary soon later, I don't think we need to give yet another kconfig. Of course, we should put a good comment around there for not keeping it for long time.
Takashi
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