[alsa-devel] DMA Physical Address through "snd_pcm_lib_malloc_pages"

Adish Kuvelker adkuvi at gmail.com
Thu Jun 24 09:22:47 CEST 2010


If I use "SNDRV_DMA_TYPE_CONTINUOUS" as a parameter to pre-allocate
function to get contiguous locations of memory and use the function
snd_dma_continuous_data() would that be correct setting for my case?
Where are the parameters of dma_addr and dma_area written to the
runtime structure?


On Thu, Jun 24, 2010 at 12:45 PM, Takashi Iwai <tiwai at suse.de> wrote:
> At Thu, 24 Jun 2010 12:38:35 +0530,
> Adish Kuvelker wrote:
>> Hello Takashi,
>> I am developing a DMA Controller driver to service the PCM out data to
>> the Audio controller on the arm-based ATLASIII procesor. In case you
>> need any more information on the architecture I can pass.
>> Since the DMA isn't on PCI bus I am pre-allocation continuous memero
>> using the "snd_pcm_lib_preallocate_pages_for_all" passing
>> SNDDRV_DMA_TYPE_DEV and "snd_dma_continuous_data" as appropriate
>> parameters.
> snd_dma_continuous_data() is only for SNDRV_DMA_TYPE_CONTINUOUS.
> In this case, the pages aren't for DMA.
> For SNDRV_DMA_TYPE_DEV, simply pass the device pointer you use.
> Takashi

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