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

[Appalayagari Sreedhar]

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 at gmail.com> wrote:
> 2011/12/22, Appalayagari Sreedhar <sreecha01 at 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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