[alsa-devel] Getting physical address of the DMA buffer
Pharaoh .
pharaoh137 at gmail.com
Wed Jun 27 10:48:13 CEST 2007
On 6/27/07, Clemens Ladisch <cladisch at fastmail.net> wrote:
> Pharaoh . wrote:
> > I have allocated the DMA buffer using snd_pcm_lib_malloc_pages() and
> > it was preallocated as:
> >
> > snd_pcm_lib_preallocate_pages_for_all(pcm,
> > SNDRV_DMA_TYPE_CONTINUOUS,
> > snd_dma_continuous_data
> > (GFP_KERNEL),
>
> SNDRV_DMA_TYPE_CONTINUOUS is for a buffer that cannot be accessed
> over DMA.
>
> What kind of bus does your hardware use, and how would you
> allocate memory for it?
>
>
> Regards,
> Clemens
>
Continuous buffers unrelated to the bus type can be allocated using
SNDRV_DMA_TYPE_CONTINUOUS right? I am referring a standard driver from
omap source tree, and the buffer allocation functions I have copied
from there and they should be same for the range of OMAPs since the
dma handling is same for them.
> SNDRV_DMA_TYPE_CONTINUOUS is for a buffer that cannot be accessed
> over DMA.
Thats why I get runtime->dma_addr as 0.
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