[alsa-devel] [3.13-rc8] AM335x BeagleBone Buffer XRUN

Jack Mitchell ml at communistcode.co.uk
Thu Jan 16 11:44:53 CET 2014

On 14/01/14 20:31, Jack Mitchell wrote:
> I am currently trying to debug a buffer overrun when capturing with the
> BeagleBone Black and Audio Cape attached on 3.13-rc8, this is pretty
> much the same setup as the am335x-evm. The following is the traceback
> captured using the XRUN_BUFFER_DEBUG kernel config option. I think an
> interrupt is taking too long to return.
> [snip

Ok, so I managed to enlarge the buffer by increasing the
max_buffer_bytes in snd_pcm_hardware capture struct. However, it doesn't
really make sense... The original value was (128*1024) which should give
a buffer of 128K, but in reality it gave a buffer of 32K. Now when I was
hacking last night it got to the point where I just started twiddling
knobs to see what would happen, and it turns out that changing the
max_buffer_bytes to (256*1024) gave me 64K of buffer. So, I don't have a
clue what is going on here, but I now have enough buffer to get the
audio data captured and written out before an overflow occurs.


  Jack Mitchell (jack at embed.me.uk)
  Embedded Systems Engineer
  Cambridgeshire, UK

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