Re: [PATCH] ASOC:DAPM: extend dapm kcontrol to support runtime route update

[Takashi Iwai <tiwai@suse.de>]

At Fri, 13 Dec 2013 19:33:46 +0800,
Nenghua Cao wrote:
> 
> Hi, Mark:
> 
> On 12/12/2013 07:07 PM, Mark Brown wrote:
> > On Thu, Dec 12, 2013 at 02:56:08AM -0800, Nenghua Cao wrote:
> > 
> > Don't top post.  Please also fix your mailer to word wrap within
> > paragaphs, it makes your mails much more legible.
> > 
> It is my fault and Thanks for your kindly reminder. I just made my
> mailer work as community's request.
> >> >    For common mix/mux which aren't related with DPCM, it doesn't need
> >> >    to do DPCM update. And it still can use the old controls. But for
> >> >    the mix/mux which impacts fe<->be link, they need to do this works.
> >> >    For them, they call use the new set of controls. I think it can
> >> >    make our code has better backward-compatibility.
> > How does this improve backwards compatibility?
> My thought is that we distinguish different requirement through flag
> (you can find dpcm_checked in my patch).

The question is rather what do you mean as "backward compatibility".

Usually backward compatibility is concerned when something new breaks
the existing ones.  In your case, always updating DPCM would work,
too, even without an extra flag; it's just suboptimal.


Takashi