Add a function to dynamically update 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 update existing controls. A separate patch needs to be made to allow ALSA Mixer to update the controls dynamically.
Signed-off-by: Dimitris Papastamos dp@opensource.wolfsonmicro.com --- Hi,
Any potentially locking related issues have been fixed now. Any comments on whether it would be advisable to use the same `numid' when I update an existing control?
Thanks, Dimitris
include/sound/control.h | 1 + sound/core/control.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 66 insertions(+), 0 deletions(-)
diff --git a/include/sound/control.h b/include/sound/control.h index e67db28..2a2fd82 100644 --- a/include/sound/control.h +++ b/include/sound/control.h @@ -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_update(struct snd_card * card, struct snd_kcontrol * kcontrol, bool add_on_update); 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, diff --git a/sound/core/control.c b/sound/core/control.c index db51e4e..1d2b524 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -368,6 +368,71 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol) EXPORT_SYMBOL(snd_ctl_add);
/** + * snd_ctl_update - update the control instance of the card + * @card: the card instance + * @kcontrol: the control instance to update + * @add_on_update: add the control if not already added + * + * Updates the given control. If the given control does not exist + * and the add_on_update 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 updated. + */ +int snd_ctl_update(struct snd_card *card, struct snd_kcontrol *kcontrol, + bool add_on_update) +{ + 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_update) + 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_update); + +/** * snd_ctl_remove - remove the control from the card and release it * @card: the card instance * @kcontrol: the control instance to remove