Hi,
I think I found a bug in the latest SDK version 7 for AM335x. The audio driver is causing a division by zero in the davinci_pcm_enqueue_dma when audio is played back as the active_serializers parameter is not set for the DMA.
This should happen within davinci_mcasp_hw_params:
dma_params->active_serializers=active_serializers;
Then audio playback works - see the whole function below:
static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params,
struct snd_soc_dai *cpu_dai)
{
struct davinci_mcasp *mcasp = snd_soc_dai_get_drvdata(cpu_dai);
struct davinci_pcm_dma_params *dma_params =
&mcasp->dma_params[substream->stream];
struct snd_dmaengine_dai_dma_data *dma_data =
&mcasp->dma_data[substream->stream];
int word_length;
u8 fifo_level;
u8 slots = mcasp->tdm_slots;
u8 active_serializers;
int channels = params_channels(params);
int ret;
ret = mcasp_common_hw_param(mcasp, substream->stream, channels);
if (ret)
return ret;
if (mcasp->op_mode == DAVINCI_MCASP_DIT_MODE)
ret = mcasp_dit_hw_param(mcasp);
else
ret = mcasp_i2s_hw_param(mcasp, substream->stream);
if (ret)
return ret;
switch (params_format(params)) {
case SNDRV_PCM_FORMAT_U8:
case SNDRV_PCM_FORMAT_S8:
dma_params->data_type = 1;
word_length = 8;
break;
case SNDRV_PCM_FORMAT_U16_LE:
case SNDRV_PCM_FORMAT_S16_LE:
dma_params->data_type = 2;
word_length = 16;
break;
case SNDRV_PCM_FORMAT_U24_3LE:
case SNDRV_PCM_FORMAT_S24_3LE:
dma_params->data_type = 3;
word_length = 24;
break;
case SNDRV_PCM_FORMAT_U24_LE:
case SNDRV_PCM_FORMAT_S24_LE:
case SNDRV_PCM_FORMAT_U32_LE:
case SNDRV_PCM_FORMAT_S32_LE:
dma_params->data_type = 4;
word_length = 32;
break;
default:
printk(KERN_WARNING "davinci-mcasp: unsupported PCM format");
return -EINVAL;
}
/* Calculate FIFO level */
active_serializers = (channels + slots - 1) / slots;
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
fifo_level = mcasp->txnumevt * active_serializers;
else
fifo_level = mcasp->rxnumevt * active_serializers;
if (mcasp->version == MCASP_VERSION_2 && !fifo_level)
dma_params->acnt = 4;
else
dma_params->acnt = dma_params->data_type;
dma_params->fifo_level = fifo_level;
dma_params->active_serializers=active_serializers;
dma_data->maxburst = fifo_level;
davinci_config_channel_size(mcasp, word_length);
return 0;
}
Please see
