[alsa-devel] [alsa-cvslog] alsa-kmirror: ALSA kernel mirror repository branch, master now at v1.0.21-334-g6739046

[Takashi Iwai]

At Thu, 12 Nov 2009 12:11:17 +0100 (CET),
Jaroslav Kysela wrote:
> 
> On Thu, 12 Nov 2009, Takashi Iwai wrote:
> 
> > At Thu, 12 Nov 2009 11:39:12 +0100,
> > I wrote:
> >>
> >> At Thu, 12 Nov 2009 10:54:02 +0100 (CET),
> >> noreply-git at alsa-project.org wrote:
> >>>
> >>> commit 6739046df36c7adf80c961bcba4870270e66dbf6
> >>> Author:     Jaroslav Kysela <perex at perex.cz>
> >>> AuthorDate: Thu Nov 12 10:15:48 2009 +0100
> >>> Commit:     Jaroslav Kysela <perex at perex.cz>
> >>> CommitDate: Thu Nov 12 10:51:48 2009 +0100
> >>>
> >>>     ALSA: hda - proc - add support for dynamic controls to mixer<->NID mapping
> >>>
> >>>     This patch adds support for dynamically created controls to proc codec file
> >>>     (Control: lines).
> >>>
> >>>     Signed-off-by: Jaroslav Kysela <perex at perex.cz>
> >>>
> >>> commit c45b73bf328cd8ace53cf39994328cf9d6548c4f
> >>> Author:     Jaroslav Kysela <perex at perex.cz>
> >>> AuthorDate: Wed Nov 11 13:43:01 2009 +0100
> >>> Commit:     Jaroslav Kysela <perex at perex.cz>
> >>> CommitDate: Thu Nov 12 10:51:16 2009 +0100
> >>>
> >>>     ALSA: hda - proc - introduce Control: lines to show mixer<->NID assignment
> >>>
> >>>     This is an initial patch to show universal control<->NID assigment in
> >>>     proc codec file. The change helps to debug codec related problems.
> >>>
> >>>     Signed-off-by: Jaroslav Kysela <perex at perex.cz>
> >>
> >> I find the second one is the nice hack, but the first (newer) one
> >> isn't good since it abuses the subdevice field of the ctl id.
> >> It is a part of API/ABI, and if we do any changes the semantics, we
> >> should define the changed behavior *beforehand* publicly.
> >
> > BTW, I don't mean that using subdevice is wrong.  Instead: if we use
> > it, let's define the proper definition first.  For example, define
> > (1 << 31) as the private (driver-specific) field bit in control.h.
> >
> > Actually, using the subdevice can make the change of snd_hda_add_ctl
> > easier, too.  Then you don't keep nid in another field but just use
> > snd_kcontrol to retrieve the nid.
> >
> > Of course, we'd need to check the existing apps (at least our own)
> > whether subdevice is really safe to change freely, though.
> 
> I think that you overlooked this code in snd_hda_add_new_ctls():
> 
>                 if (knew->subdevice & (1<<31)) {
>                          nid = knew->subdevice & 0xffff;
>                          kctl->id.subdevice = 0;
>                  } else {
>                          nid = 0;
>                  }
> 
> The subdevice value for nid contents will never leave the HDA code.

Yep, I overlooked that.


Takashi