On Mon, 11 Jan 2021 09:05:04 +0100
Takashi Iwai [off-list ref] wrote:

On Sun, 10 Jan 2021 18:41:46 +0100,
Lauri Kasanen wrote:

quoted

It was returning nextpos, but the pointer printk was in bytes. 8192
bytes = 2048 frames.

OK, then it must be right.

Then I suppose that the update of pos should be changed in a different
way; it should always point to the previous nextpos.  That is,
something like:

static void n64audio_push(struct n64audio_t *priv, uint8_t irq)
{
	....
	if (irq)
		priv->chan.pos = priv->chan.nextpos;
	priv->chan.nextpos += count;
	priv->chan.nextpos %= priv->chan.bufsize;

If we use nextpos as the position, it'll lead to the double steps at
the first IRQ handling without snd_pcm_period_elapsed() call (the
first step missed it), and this may confuse PCM core.

This almost works, speed is correct, but the last part is played twice.

I wonder if the first, non-irq push should just push a silent buffer,
and not update pos or nextpos at all.

- Lauri