Re: [alsa-devel] get rid of controls with snd_ctl_remove

At Fri, 29 Aug 2008 14:54:42 +0200, Harald Radke wrote:

Hi there!

Please be patient with me, I am quite inexperienced with alsa programming, so this might be a dumb question:

We have a WM8750 working in our PDA, the codec is working so far but I want to remove some of the control since they aren't needed.

Instead of copying the wm8750.c file and adjusting it, I want to write another module which basically get rid of those controls, something like:

[...]

static const char* unused_controls[] = {"AAAA", "BBBB,"CCCC"};

    struct snd_kcontrol *ctl;

    list_for_each_entry(ctl, &card->controls, list)

You can't use list_for_each_entry() together with removal. Use list_for_each_entry_safe() for such a purpose.

But...

      for(i=0; i <  ARRAY_SIZE(unused_controls); i++)
        if (!strcmp(unused_controls[i],ctl->id.name)) {
          down_write(&card->controls_rwsem);
          snd_ctl_remove(card,ctl);
          up_write(&card->controls_rwsem);
          break;
        }

It'd be easier like the following:

for (i = 0; i < ARRAY_SIZE(unused_controls); i++) { struct snd_ctl_elem_id id; memset(&id, 0, sizeof(id)); strcpy(id.name, unused_controls[i]); id.iface = SNDRV_CTL_ELEM_IFACE_MIXER; snd_ctl_remove_id(card, &id); }

Takashi