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>
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@ -113,6 +113,7 @@ struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new * kcontrolnew, v
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void snd_ctl_free_one(struct snd_kcontrol * kcontrol);
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int snd_ctl_add(struct snd_card * card, struct snd_kcontrol * kcontrol);
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int snd_ctl_remove(struct snd_card * card, struct snd_kcontrol * kcontrol);
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int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol, bool add_on_replace);
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int snd_ctl_remove_id(struct snd_card * card, struct snd_ctl_elem_id *id);
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int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, struct snd_ctl_elem_id *dst_id);
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int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
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@ -365,6 +365,70 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
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EXPORT_SYMBOL(snd_ctl_add);
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/**
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* snd_ctl_replace - replace the control instance of the card
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* @card: the card instance
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* @kcontrol: the control instance to replace
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* @add_on_replace: add the control if not already added
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*
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* Replaces the given control. If the given control does not exist
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* and the add_on_replace flag is set, the control is added. If the
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* control exists, it is destroyed first.
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*
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* Returns zero if successful, or a negative error code on failure.
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*
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* It frees automatically the control which cannot be added or replaced.
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*/
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int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
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bool add_on_replace)
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{
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struct snd_ctl_elem_id id;
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unsigned int idx;
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struct snd_kcontrol *old;
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int ret;
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if (!kcontrol)
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return -EINVAL;
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if (snd_BUG_ON(!card || !kcontrol->info)) {
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ret = -EINVAL;
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goto error;
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}
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id = kcontrol->id;
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down_write(&card->controls_rwsem);
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old = snd_ctl_find_id(card, &id);
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if (!old) {
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if (add_on_replace)
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goto add;
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up_write(&card->controls_rwsem);
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ret = -EINVAL;
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goto error;
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}
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ret = snd_ctl_remove(card, old);
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if (ret < 0) {
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up_write(&card->controls_rwsem);
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goto error;
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}
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add:
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if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
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up_write(&card->controls_rwsem);
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ret = -ENOMEM;
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goto error;
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}
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list_add_tail(&kcontrol->list, &card->controls);
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card->controls_count += kcontrol->count;
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kcontrol->id.numid = card->last_numid + 1;
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card->last_numid += kcontrol->count;
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up_write(&card->controls_rwsem);
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for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
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snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
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return 0;
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error:
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snd_ctl_free_one(kcontrol);
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return ret;
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}
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EXPORT_SYMBOL(snd_ctl_replace);
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/**
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* snd_ctl_remove - remove the control from the card and release it
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* @card: the card instance
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