Hi,
Trent Piepho wrote:
You need to make sure the buffer size is an integer multiple of the period size if you wrap like this.
Yeah I have to take care of this but right now my buffersize is 32768 bytes and the period size is 4096 bytes which should work I think.
I found that ALSA would call TRIGGER_STOP if it detected an overrun.
Yeah that's right. I guess this is my case because xrun() is getting called somewhere. So how can I fix this underrun problem?
Check the value returned for every call of your pointer callback. I found out that ALSA was calling the pointer callback before the first IRQ, which was something I hadn't planned on and the values confused ALSA.
That's not my case. pcm_pointer gets called after the first DMA transaction is finished. (DMA transfer finished callback gets called before pcm_pointer) Also the values which are returned by pcm_pointer look quite reasonable. (see also my very first posting in this thread, look for the printk's "pcm_pointer returns <value>")
Thanks for your effort,
Markus Franke