[alsa-devel] about sound/core/pcm_lib.c:1997: capture read error (DMA or IRQ trouble?)

[Clemens Ladisch]

Akio wrote:
> Clemens Ladisch <cladisch <at> fastmail.net> writes:
> > Akio wrote:
> > > Clemens Ladisch <cladisch <at> fastmail.net> writes:
> > > > I would have guessed that some 32-bit counter has overflowed, but at
> > > > 48 kHz, a frame counter would overflow after slightly less than
> > > > 25 hours.
> > > 
> > > Thanks for Clemens. Could you tell me the counter's name and which layer does it?
> > > in alsa driver or in alsa lib or in alsa core module?
> > 
> > I'm not aware of any such bug in the ALSA framework.  I'd guess this is
> > some problem with your driver.
> > 
> > What sample frequency are you using?
> 
>   in my case, the sampling rate is 16k,

At 16 kHz, a 32-bit counter overflows after about 74.5 hours.

> what is the unit of the counter? period counts or samples?

I do not know what counter this could be.  I'm just guessing that _some_
counter overflows; this would fit the symptoms you've described.

> > > snd_pcm_prepare does not work.
> > 
> > What error does it return?
> 
>   I use strerr to get the error message, and it tell me "Input/Output
>   Error"

This error code is returned by the driver.  Which driver are you using?


Regards,
Clemens