Unexpected hw_pointer value (pcm_lib.c)

Unexpected hw_pointer value (pcm_lib.c)

[Manuel Jander]

Hello,

Can anyone tell me how does pcm_lib.c cope with buffer wrap around ?
I'm missing something like:

delta =  pointer_current - pointer_prev;
if (delta < 0)
   delta += period_size;
 
Well, indeed i'm getting some warnings then and when, after i enabled
the ALSA debug option:

ALSA sound/core/pcm_lib.c:216: Unexpected hw_pointer value (stream = 0,
delta: -586, max jitter = 8192): wrong interrupt acknowledge?

Delta has a negative value, thus the if statement :

if ((snd_pcm_uframes_t)delta < runtime->buffer_size / 2) {
    snd_printd("Unexpected hw_pointer value (stream = %i, d
    return 0;
}

... is always true. Well, as the code looks like, the situation when the
period pointer wraps around back to cero isn't handled correctly. Or is
that handled by other means ? Maybe i just oversaw something. Can anyone
give me more insight over this ? Thanks...

Best Regards

Manuel Jander.




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