[Sound-open-firmware] about multiple BE dai_links support

[Pierre-Louis Bossart]

>>>>> 2. Pierre brought this up in another email, will the ID's be
>>>>> sequential  across different DAI types? Or will they start at 0?
>>>
>>> In my opinion, it is more important that this ID should be unique,
>>> usually we will make them sequential and start at 0, but
>>> theoretically, it is not mandatory, nothing can prevent you using ids like 1, 3, 5,
>> 6, 8,...
>>
>> IDs are aligned 1:1 to BE DAI links so must be unique. They should start at 0 and I
> 
> Agree.
> 
>> would not expect to see gaps.
> 
> That's OK, let's note about this and don't allocate them with gaps in machine driver then.

That's a bad assumption. For development or quirks, you may want to e.g. 
comment out a back-end on  a specific machine driver (such as DMIC or 
SSP if there is no codec connected) and still expect HDMI to work - in 
that case the BE ID would not start at zero and might not be sequential. 
Why do we care about the BE ID value anyways? they need to be unique, 
period. that's the only thing we should assume.