On Mon, 11 Jan 2021 11:11:39 +0100 Takashi Iwai <tiwai@xxxxxxx> wrote: > > This almost works, speed is correct, but the last part is played twice. > > Oh yes, at the last IRQ, the push should be avoided. > I guess that the code order should be changed to the following way: > > 1. advance the position for a period size > 2. call snd_pcm_period_elapsed() > 3. check if the stream is still running > 4. copy the next chunk and update nextpos This order gives correct pointer advancing etc, but now it's hitting a new problem: the pcm core is reusing the buffer from under the audio card. It's writing new data to the area that is currently being read by DMA. I assume the core expects DMA to be instant, but in this card's case it's ondemand, reading bytes as needed. By restoring the memcpy buffer, I get good audio with this new order (sans occasional crackling due to the memcpy taking too long). - Lauri
