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ALSA: Add snd_ctl_activate_id()

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Added a new API function snd_ctl_activate_id() for activate / inactivate
the control element dynamically.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
This commit is contained in:
Takashi Iwai 2008-08-29 16:09:01 +02:00 committed by Mark Brown
parent 80e1b84ffe
commit 3cbdd75331
2 changed files with 48 additions and 0 deletions
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2
include/sound/control.h
View file

@ -115,6 +115,8 @@ int snd_ctl_add(struct snd_card * card, struct snd_kcontrol * kcontrol);
int snd_ctl_remove(struct snd_card * card, struct snd_kcontrol * kcontrol);
int snd_ctl_remove_id(struct snd_card * card, struct snd_ctl_elem_id *id);
int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, struct snd_ctl_elem_id *dst_id);
int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
int active);
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);

46
sound/core/control.c
View file

@ -465,6 +465,52 @@ error:
return ret;
}
/**
* snd_ctl_activate_id - activate/inactivate the control of the given id
* @card: the card instance
* @id: the control id to activate/inactivate
* @active: non-zero to activate
*
* Finds the control instance with the given id, and activate or
* inactivate the control together with notification, if changed.
*
* Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
*/
int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
int active)
{
struct snd_kcontrol *kctl;
struct snd_kcontrol_volatile *vd;
unsigned int index_offset;
int ret;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
if (kctl == NULL) {
ret = -ENOENT;
goto unlock;
}
index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
vd = &kctl->vd[index_offset];
ret = 0;
if (active) {
if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
goto unlock;
vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
} else {
if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
goto unlock;
vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
}
ret = 1;
unlock:
up_write(&card->controls_rwsem);
if (ret > 0)
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
return ret;
}
EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
/**
* snd_ctl_rename_id - replace the id of a control on the card
* @card: the card instance