[alsa-devel] Trouble understanding ALSA's DMA buffers

[Timur Tabi]

Takashi Iwai wrote:

> Yes.  And the "ping-poing" is the case that you have two periods in a
> ring buffer.

Ok, I understand the 'periods' concept now, thanks.

So when/where does ALSA copy data to the DMA buffer?  Isn't there supposed to be some kind 
of callback where ALSA calls the driver and says, "here's some data, please copy it to 
your DMA buffer?"

Or does ALSA do all the copying itself whenever the driver calls snd_pcm_period_elapsed()?

-- 
Timur Tabi
Linux Kernel Developer @ Freescale