Re: [alsa-devel] pcm timer resolution out of range (rate = 0, period_size = 1), Division by zero in kernel

23 Dec 2011


      Hi Raymond,
We are working with DM368 processor and cx20709 conexant external
codec interfaced via McBSP.
The davinci pcm hw params is below. (from davinci-pcm.c file)
static struct snd_pcm_hardware davinci_pcm_hardware = {
        .info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
                 SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
                 SNDRV_PCM_INFO_PAUSE),
        .formats = (SNDRV_PCM_FMTBIT_S16_LE),
        .rates = (SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 |
                  SNDRV_PCM_RATE_22050 | SNDRV_PCM_RATE_32000 |
                  SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 |
                  SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000 |
                  SNDRV_PCM_RATE_KNOT),
        .rate_min = 8000,
        .rate_max = 96000,
        .channels_min = 2,
        .channels_max = 2,
        .buffer_bytes_max = 128 * 1024,
        .period_bytes_min = 32,
        .period_bytes_max = 8 * 1024,
        .periods_min = 16,
        .periods_max = 255,
        .fifo_size = 0,
};
and we are configuring from user space using OSS ioctl for Speed.
Format and Bits Per Sample.
Speed = 8kHz/16kHz
Format = AFMT_S16LE
Bits Per Sample = 16
Channels = Stereo/Mono
I am new to ALSA and OSS. Please let me know if you need further details.
Thank you,
Sreedhar.
On 12/23/11, Raymond Yau superquad.vortex2@gmail.com wrote:
...
2011/12/22, Appalayagari Sreedhar sreecha01@gmail.com:
...
Hi,
We are working with 2.6.32 kernel. we are working with ALSA model
codec driver for conexant chipset. we are using OSS emulation for
audio playback and recording.
we are not setting the fragmenttaion block using OSS ioctl function
(SNDCTL_DSP_SETFRAGMENT) , assuming that it will be taken care by the
ALSA framework based on the sampling rate, bits per sample etc.
we are facing the below issue randomly.
ALSA sound/core/pcm_timer.c:71: -calling VIDIOC_pcm timer resolution
out of range (rate = 0, period_size = 1)
Division by zero in kernel.
Do your controller really support 1 frame per period (period_size = 1) ?
What is the value of .period_bytes_min and other parameters in
snd_pcm_hardware and format supported ?
...
We tried to program the fragmentation block after the sampling rate,
bits per sample etc are configured. it is working fine for 5 or 6
iterations for recording and playback.
after that the audio quality is gone bad. the audio is not smooth and
it is sharp.
could you please help to resolve this problem.

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