Re: [RFC PATCH 0/3] Separate BE DAI HW constraints from FE ones

From: Mark Brown
Date: Fri Apr 16 2021 - 14:56:07 EST


On Fri, Apr 16, 2021 at 11:47:01AM -0500, Pierre-Louis Bossart wrote:
> On 4/16/21 11:31 AM, Mark Brown wrote:

> > Not really written down that I can think of. I think the next steps
> > that I can think of right now are unfortunately bigger and harder ones,
> > mainly working out a way to represent digital configuration as a graph
> > that can be attached to/run in parallel with DAPM other people might
> > have some better ideas though. Sorry, I appreciate that this isn't
> > super helpful :/

> I see a need for this in our future SoundWire/SDCA work. So far I was
> planning to model the entities as 'widgets' and lets DAPM propagate
> activation information for power management, however there are also bits of
> information in 'Clusters' (number of channels and spatial relationships)
> that could change dynamically and would be interesting to propagate across
> entities, so that when we get a stream of data on the bus we know what it
> is.

Yes, I was thinking along similar lines last time I looked at it - I was
using the term digital domains. You'd need some impedence matching
objects for things like SRCs, and the ability to flag which
configuration matters within a domain (eg, a lot of things will covert
to the maximum supported bit width for internal operation so bit width
only matters on external interfaces) but I think for a first pass we can
get away with forcing everything other than what DPCM has as front ends
into static configurations.

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