Re: [PATCH] aplay: support no period wakeup option in argument

[Takashi Iwai <tiwai@suse.de>]

On Thu, 27 Dec 2018 07:46:57 +0100,
S.j. Wang wrote:
> 
> I still have two questions:
> 1. It seems the no-period-wakeup feature should be dropped for it isn't recommended
>    By alsa, right?  I still found some driver in kernel support it, what's the reason?
> 
> 2. Shall we add this option in aplay for it is feature that alsa support, even it is optional?

As Sakamoto-san already mentioned, no-period-wakeup is nothing but an
optional feature for very specific applications and setup, and it's
still valid and useful.

The condition to use this option is:
- If a hardware may perform DMA continuously on a ring buffer (a la 
  free-wheel mode), and
- Application doesn't need the wakeup from kernel at each PCM period,
  but it manages the stream transfer timing by itself.
 
aplay doesn't satisfies the latter, hence adding such a command line
option makes no sense.  But, it doesn't mean that no-period-wakeup is
useless.  It can work well for specific applications like PulseAudio.


Takashi