Data Transfer Question

Data Transfer Question

[Charles Eidsness]

I'm working on an ALSA driver for an embedded MIPS processor and am 
having trouble getting it to run at a rate > 16kHz.

What I've notice when it's running at 16kHz or less the ALSA API is 
calling  my pointer function before the first interrupt, i.e.

START
call pointer
interrupt (which calls snd_pcm_period_elapsed)
call pointer
call pointer
interrupt (which calls snd_pcm_period_elapsed)
.
.
.

And everything sounds fine, but when I run at > 16kHz it doesn't call 
the pointer function before the first interrupt, and after the first 
interrupt it stops and then starts, i.e.

START
interrupt (which calls snd_pcm_period_elapsed)
call pointer
STOP
START
interrupt (which calls snd_pcm_period_elapsed)
call pointer
STOP
.
.

And ends up sounding very choppy. Can anyone help shed some light on 
what's going on? Why is the API calling the pointer function before the 
first interrupt?

You can find my code here: 
http://members.rogers.com/charles.eidsness/au1000.c

Thanks,
Charles





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