Radivoje Jovanovic wrote:

I am allocating memory for the buffers in my init call by doing: snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS, snd_dma_continuous_data(GFP_KERNEL), 256*1024, 256*1024);

in my hw_params call I have: ret= snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));

here is the output from my hw_params call:

called snd_pcm_lib_malloc_pages return=1 params_buffer_bytes(hw_params)=32768 Size of DMA area=32768 Buffer size in bytes=262144 Buffer virt address=9dc00000 Buffer phys address=0

Now I am not sure why is my buffer size bigger than my DMA area.

You did not say which values are output, but 262144 is 256*1024, so this is the preallocated buffer. The DMA is what is actually used with the current hw_params.

I assume that memory is not linear because of that

SNDRV_DMA_TYPE_CONTINUOUS gives you continguous pages.

and that is why I do not have phys address to the buffer.

It doesn't give you the physical address; it looks as if this memory is intended to be accessed only by the CPU.

To get coherent memory with a DMA address for a specific device, use SNDRV_DMA_TYPE_DEV. (This must be supported by your architecture.)

Regards, Clemens