[alsa-devel] PulseAudio and SNDRV_PCM_INFO_BATCH

[Raymond Yau]

2015-6-22 下午2:43 於 "Lars-Peter Clausen" <lars at metafoo.de> 寫道：
>
> On 06/22/2015 04:35 AM, Raymond Yau wrote:
>>
>>
>>  >
>>  > DMA_RESIDUE_GRANULARITY_BURST means it can report the position with a
>> granularity of a few samples. Typically half the audio FIFO size.
>>  >
>>  >
>>
>> How many soc driver/platform dma engine support
DMA_RESIDUE_GRANULARITY_BURST ?
>
>
> Not sure, maybe half of them. But most of the time it is a software
restriction rather than a hardware restriction and more and more drivers
are supporting it.

https://bugs.freedesktop.org/attachment.cgi?id=107650

snd_rpi_hifiberry_amp

granularity seem 4 frames most of the time but sometime there is a large
delay between 3584 and 3988 ,seem cannot reach 4096

Available: 3580, loop iteration: 420
Available: 3584, loop iteration: 421
Available: 3988, loop iteration: 422
Available: 3996, loop iteration: 423
Available: 4004, loop iteration: 424
Available: 4012, loop iteration: 425

Are the pointer callback really use value read from hardware register or
value calculated from clock ?