l9jj wrote:

can anyone help me to figure out the concepts between period_size ,buffer_size and boundary size? n * period_size = buffer_size?

Yes. On many devices, n is not required to be an integer.

m * buffer_size = boundary_size?

Yes, where m is very big. In applications, the actual value of the boundary size does not matter (except as a special value for some sw params).

and how the dma buffer mapped to the alsa buffer?

The DMA buffer _is_ the ALSA buffer.

Regards, Clemens