On 10/02/2020 16.38, Takashi Iwai wrote:
> On Mon, 10 Feb 2020 15:28:44 +0100,
> Peter Ujfalusi wrote:
>>
>> Hi Takashi,
>>
>>>> --- a/sound/soc/soc-pcm.c
>>>> +++ b/sound/soc/soc-pcm.c
>>>> @@ -1151,7 +1151,7 @@ static snd_pcm_uframes_t soc_pcm_pointer(struct snd_pcm_substream *substream)
>>>> }
>>>> delay += codec_delay;
>>>>
>>>> - runtime->delay = delay;
>>>> + runtime->delay += delay;
>>>
>>> Is it correct?
>>> delay already takes runtime->delay as its basis, so it'll result in a
>>> double.
>>
>> The delay here is coming from the DAI and the codec.
>> The runtime->delay hold the PCM (DMA) caused delay.
>
> Well, let's take a look at soc_pcm_pointer():
>
> /* clearing the previous total delay */
> runtime->delay = 0;
>
> offset = snd_soc_pcm_component_pointer(substream);
>
> /* base delay if assigned in pointer callback */
> delay = runtime->delay;
>
> delay += snd_soc_dai_delay(cpu_dai, substream);
>
> for_each_rtd_codec_dai(rtd, i, codec_dai) {
> codec_delay = max(codec_delay,
> snd_soc_dai_delay(codec_dai, substream));
> }
> delay += codec_delay;
>
> runtime->delay = delay;
>
> So, the code reads the current runtime->delay and saves it as delay
> variable. Then it adds the max delay from codec DAIs, and stores back
> to runtime->delay.
>
> If we change the last line to
> runtime->delay += delay;
> it'll add to the already existing value again, so it'll be doubly if
> runtime->delay was non-zero beforehand.
Yes, you are right.
The change is added by
9fb4c2bf130b ASoC: soc-pcm: Use delay set in component pointer function
which I have missed, apparently.
> That said, judging from the code, I believe the current soc-pcm.c code
> needs no change.
Yes, there is no need to change soc-pcm.
>
>
> thanks,
>
> Takashi
>
- Péter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
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