[AudioI] Dual setup

[Matt]

It is an interesting question.

We know that you can get a GPIO card + HDMI I2S output working at the 
same time : 
https://lists.audioinjector.net/pipermail/people/2020-March/000021.html

The default answer is always no. However it may have work arounds ... 
but I am not 100% sure it can be done.

The first problem would be in probing the sound card, see the ISOLATED 
sound card probe for example :

https://github.com/raspberrypi/linux/blob/rpi-4.19.y/sound/soc/bcm/audioinjector-isolated-soundcard.c#L123

There the CPU/platform and codec data is populated. Will ALSA SoC spit 
the dummy if two cards are registered for the same I2S bus ? Most 
likely. If not, then it may overwrite the SoC core with the most recent 
one added. In which case, both would be plugged in but only one would be 
active.

Imagine however this worked. For example, imagine you worked out how to 
register one for playback and one for capture.

The next problem is who will control the clock ?

I suspect with a lot of hacking you could find limited functionality. 
However my experience is that Linux frowns upon upstreaming hacking ... 
which means you could get something to work on your desk, but it 
wouldn't become mainstream :)

However I can see lots of ways to try work arounds. For example, imagine 
you had many of the same sound card hooked up. Say you wanted to do DAC 
only. You could find a way to output with one card as master and the 
others as slave ... however in this case all output cards would play 
back exactly the same saples - but their mixers should be independently 
controllable :)

Matt

On 4/5/20 3:09 pm, Robert Bielik via People wrote:
>
> Hi,
>
> I’d like to ask if it is possible to have a dual configuration, i.e. 
> enabling both the stereo and the octocard (in config.txt) ? My guess 
> is that the kernel will try to initialize the chipsets and fail on the 
> one not connected.  Has anyone tried this ?
>
> Regards
>
> /Rob
>
> The information in this email (including any attachments) may contain 
> confidential and/or proprietary material. Any review, retransmission 
> or use of this information by persons or entities other than the 
> intended, authorized recipient is prohibited. If you received this 
> email in error, please notify the sender and delete the material. For 
> information regarding how Dirac handles personal data, please visit 
> https://www.dirac.com/privacy-policy.
>
-- 
Our latest product launching now on Kickstarter :
https://bit.ly/2Qr1557
Checkout the community email list :
https://lists.audioinjector.net/mailman/listinfo/people

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.audioinjector.net/pipermail/people/attachments/20200504/c35010f9/attachment.htm>