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ALSA: Add snd_ctl_replace() to dynamically replace a control 

Add a function to dynamically replace a given control.  If the
control does not already exist, a third parameter is used to determine
whether to actually add that control.  This is useful in cases where
downloadable firmware at runtime can add or replace existing controls.
A separate patch needs to be made to allow ALSA Mixer to render the
replaced controls on the fly.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Dimitris Papastamos 2011-03-16 12:16:39 +00:00 committed by Takashi Iwai
parent 1872f58995
commit 66b5b9722b
2 changed files with 65 additions and 0 deletions
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1
include/sound/control.h
View File

@ -113,6 +113,7 @@ struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new * kcontrolnew, v
void snd_ctl_free_one(struct snd_kcontrol * kcontrol);
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_replace(struct snd_card *card, struct snd_kcontrol *kcontrol, bool add_on_replace);
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,

64
sound/core/control.c
View File

@ -365,6 +365,70 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
EXPORT_SYMBOL(snd_ctl_add);
/**
* snd_ctl_replace - replace the control instance of the card
* @card: the card instance
* @kcontrol: the control instance to replace
* @add_on_replace: add the control if not already added
*
* Replaces the given control. If the given control does not exist
* and the add_on_replace flag is set, the control is added. If the
* control exists, it is destroyed first.
*
* Returns zero if successful, or a negative error code on failure.
*
* It frees automatically the control which cannot be added or replaced.
*/
int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
bool add_on_replace)
{
struct snd_ctl_elem_id id;
unsigned int idx;
struct snd_kcontrol *old;
int ret;
if (!kcontrol)
return -EINVAL;
if (snd_BUG_ON(!card || !kcontrol->info)) {
ret = -EINVAL;
goto error;
}
id = kcontrol->id;
down_write(&card->controls_rwsem);
old = snd_ctl_find_id(card, &id);
if (!old) {
if (add_on_replace)
goto add;
up_write(&card->controls_rwsem);
ret = -EINVAL;
goto error;
}
ret = snd_ctl_remove(card, old);
if (ret < 0) {
up_write(&card->controls_rwsem);
goto error;
}
add:
if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
up_write(&card->controls_rwsem);
ret = -ENOMEM;
goto error;
}
list_add_tail(&kcontrol->list, &card->controls);
card->controls_count += kcontrol->count;
kcontrol->id.numid = card->last_numid + 1;
card->last_numid += kcontrol->count;
up_write(&card->controls_rwsem);
for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
return 0;
error:
snd_ctl_free_one(kcontrol);
return ret;
}
EXPORT_SYMBOL(snd_ctl_replace);
/**
* snd_ctl_remove - remove the control from the card and release it
* @card: the card instance