[alsa-devel] Getting physical address of the DMA buffer

[Pharaoh .]

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.