[alsa-devel] [RFC][PATCH 0/8] ALSA: dice: constrain PCM substreams to current sampling transfer frequency

[Takashi Iwai]

On Sun, 15 Nov 2015 10:25:28 +0100,
Takashi Sakamoto wrote:
> 
> Hi,
> 
> This patchset adds a constrain to ALSA dice driver to start PCM
> substreams and AMDTP packet transferring just at current sampling
> transfer frequency.
> 
> Dice hardware doesn't allow drivers to get supported combinations
> between sampling rate and PCM channels. ALSA dice driver should follow
> to the hardware design, though current ALSA driver has some
> over-specifications. As a result, the driver has several issue and
> brings inconvenience to users.
> 
> This patchset consists of two parts:
>  * 01-05: to add constrain to current sampling transfer frequency and related
> 	  code cleanup
>  * 06-08: to ensure and stabilize AMDTP packet transmission
> 
> As a result, userspace applications can request PCM substreams at current
> sampling transfer frequency. Therefore, when users want to start PCM
> substreams at different rate, they should set the rate in advance by the
> other ways (i.e. ffado-dbus-server/ffado-mixer).

This sounds rather like a step backward.  Why can't the driver set the
rate if it's the only first and exclusive user?


thanks,

Takashi