Re: [PATCH] [RFC] ASoC: Conditional PCM support

[Cezary Rojewski <cezary.rojewski@xxxxxxxxx>]

On 2024-09-10 10:14 PM, Mark Brown wrote:
> On Thu, Aug 22, 2024 at 03:57:22PM +0200, Cezary Rojewski wrote:
>
> > You've shared many scenarios, I do not think we can cover all of them here
> > and while I could agree that current FE/BE (DPCM?) design did not age well,
> > we're entering "rewrite how-to-pcm-in-linux" area.
> > If general opinion is:
> > 	it's too much, we have to rewrite for the framework to scale
> > 	into the next 20 years of audio in Linux
>
> > then my thoughts regarding current review are:
> > 	if the avs-driver needs sideband interface, so be it, but do it
> > 	locally rather than polluting entire framework. Switch to the
> > 	framework-solution once its rewritten.
>
> On this bit as I mentioned in the prior reply there's been ideas for
> redesigning how we tackle digital audio which I think there's general
> agreement would be the best way forwards.  DPCM is very fragile and
> creaking at the seams, it can't really represent scenarios like the
> sideband case you've mentioned well.  OTOH a redesign is a very big lift
> and there's never really a point where it seems constructive to actually
> block things on it so long as everyone involved is OK with what's going
> on.
>
> The upshot is that while I'd be *really* happy to see investment in the
> framework side of things I probably wouldn't block a driver specific or
> DPCM solution simply on the grounds that it's messy.  DPCM would need
> buy in from other people using DPCM of course, and hopefully at some
> point someone with one of these issues will find that the cost of
> maintaining a bodge is going to be enough to push them to do the work
> (or someone will have free time to just work on the issue).

From my experience when it comes to redesigning/rewriting entire 
project, the "upgrade an already running train" strategy does not work, 
so I'd not recommend that.

Instead, I'd suggest to have a second, separate DPCM implementation 
present next to the existing one and have users opt in during a 
so-called deprecation period of the existing one. Once certain amount of 
time passes, switch all of them. Clean slide also makes it easier for a 
developer to be creative.

Do you view the second option as viable?