[alsa-devel] [PATCH 0/4] McBSP smart idle and DMA op mode updates for ASoC

Jarkko Nikula jhnikula at gmail.com
Wed May 19 16:50:05 CEST 2010

On Wed, 19 May 2010 15:27:35 +0300
Peter Ujfalusi <peter.ujfalusi at nokia.com> wrote:

> > The sysfs set interface implies userspace having knowledge of driver
> > capabilities and configuration in order to safely toggle between the two
> > DMA modes. Imo, the mcbsp client driver should be the only entity
> > configuring it's DMA modes (in a safe manner) depending on the use case.
> Furthermore, if there is a need for 'Use Cases', than the machine driver can 
> provide user control to switch between them.
> The thing is that in most cases these are trivial, and mostly the same settings, 
> but if you throw a codec like the tlv320dac33 into the mix, which has it's own 
> FIFO, than things gets complicated.
> The user (the real one, not the developer) has several settings scattered all 
> around the place, and those has to be configured in harmony.
> The only place is to do this, is in the machine driver, whihc than can build up 
> 'scenarios', and configure the things in synchronized manner.
Yes and I think only very few developers know what to do with those op
mode and threshold sysfs controls so most probably they are unused.
Then machine drivers setting them automatically/with some control could
give us more testing base.

But as those sysfs controls are there we must preserve them for a
release cycle or two in case if someone is using them. At least Linus
or Andrew may complain about removal of them.


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