On 01/02/2023 14:44, Jaroslav Kysela wrote:
> On 01. 02. 23 13:32, Peter Ujfalusi wrote:
>
>> +static snd_pcm_sframes_t sof_ipc4_pcm_delay(struct snd_soc_component
>> *component,
>> + struct snd_pcm_substream *substream)
>> +{
>
> ...
>
>> +
>> + /*
>> + * Handle 32-bit counter wrap around, which would happen
>> + * for a 48khz 2ch stream in 24.855 hours
>> + */
>> + link_ptr = tmp_ptr & UINT_MAX;
>> +
>> + host_ptr = substream->runtime->status->hw_ptr;
>> +
>> + if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
>> + return host_ptr - link_ptr;
>> +
>> + return link_ptr - host_ptr;
>
> I don't think that this calculation is fine for the wrap point. The
> hw_ptr is in range 0..pcm_boundary not UINT_MAX.
That is true. Our link counter is u64 (and it is counting the bytes, not
a real DMA position) so I can
tmp_ptr %= substream->runtime->boundary;
then handle the wrap of both later.
> Also, you should consider the underrun/overrun situations.
>The simple substraction is not enough to handle this correctly.
Yes, you are right. I will send v2 right away(ish)
Thanks,
Péter
