[alsa-devel] Multiple codecs on the same DAI

[Ricard Wanderlof]

On Wed, 6 Dec 2017, Mark Brown wrote:

> On Wed, Dec 06, 2017 at 01:54:38PM +0100, Ricard Wanderlof wrote:
> 
> > How about non-sound devices, for instance if there is a chip solely for 
> > managing the microphone power but it's not actually part of the codec. Is 
> > it reasonable to bring it in as an aux device too, even though there's 
> > actually no sound going through it?
> 
> That just sounds like a regulator?  I'd expect that just to be used as a
> supply as normal.

You mean as a DAPM widget?

>  What audio specific control would this device be provdiing?

What it does provide is current sensing if the connected device draws too 
much power, although it does not automatically shut off the connected 
device if that is the case, so a small driver is required to shut down the 
output in the case of overcurrent. There's also a requirement to be able 
to read the overcurrent status. One approach is to implementet the whole 
thing as an auxilliary device, with one ALSA control to control the power, 
and a read only control to read the overcurrent status.

So, no, it's not really audio specific, and furthermore it's not just 
providing a power output the way a regulator would.

It could of course be implemented as a completely separate device, but 
hardware wise it is still an integrated part of the audio solution.

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30