[alsa-devel] HDAudio period/buffer sizes

[Raymond Yau]

2011/7/27 Takashi Iwai <tiwai at suse.de>:
> At Tue, 26 Jul 2011 14:23:40 -0500,
> Pierre-Louis Bossart wrote:
>>
>> that the buffer itself was already aligned to 128 bytes from the
>> > very beginning as it's allocated via dma_alloc_coherent().
>> > The fact that the commit fixes the real problem means that the buffer
>> > size must be aligned, too, at least for some hardware.
>>
>> I checked internally and the reply was "There is no requirement the buffer
>> must be 128 byte multiples.  As long as it is integer number of samples, we
>> are good."
>>
>> What's the best way to deal with it? Add a driver option? A compilation
>> option?
>
> I'd say a driver option since this must be dynamically adjustable.
> Care to make a patch?
>
> For 3.2 (after 3.1 merge window), we can disable 128-bytes limit as
> default again for testing.  If someone hits the problem, he can switch
> easily and we can investigate more at this time.
>
>
The patch seem fix the problem of
snd_pcm_hw_params_set_period_time_near() to 120ms at 11025Hz for those
ad198x codec which are the only HDA codecs which support 11025Hz and
22050Hz

Does it mean that the period_bytes_min =128 can also be removed to
achieve lowest latency ?