[alsa-devel] [RFC PATCH] ALSA: split params refinement to seperated file

[Takashi Iwai]

At Tue, 9 Jun 2015 18:57:11 +0100,
Mark Brown wrote:
> 
> On Mon, Jun 08, 2015 at 11:21:17AM +0200, Takashi Iwai wrote:
> 
> > Just begin with adding ifdefs instead of reshuffling the code.  This
> > will make easier to understand what you're going to change.  At least,
> > it's good enough for RFC.  After that, we can refactor the code.
> 
> Plus if the patches get applied it at least makes it easier for people
> who do decide to do such major surgery.
> 
> > Removing the hw constraints refinement is rather a radical change.
> > It's a part of the PCM core functionality, and removing it means that
> > the driver has no ways to refuse the incompatible parameters even if
> > it knows it's broken.  So, IMO, this is the very last resort.  We can
> > start from ripping off lower hanging fruits.
> 
> Indeed, part of the reason I was asking about the split was to help me
> figure out what takes the place of constraints - sounds like nothing?  I
> wonder if we could have cards support this by providing fixed
> configurations that we could check against using less code or something.

I think it's possible to reduce the hw refine part.  But, the question
is whether a kernel driver should trust user-space blindly.  The
removal of *full* hw constraints means that, and I'm worried by lack
of safety.

> But like you say, we *must* have some other room for improvement.

Yes, let's see other things we can cut off.  For example, the PCM
timer is easy to trim.  It's used by dmix, but most apps / backends
don't need it at all.  Then the whole ALSA timer component can be
removed, too.


Takashi