[PATCH 1/2] ALSA: Add snd_ctl_update() to dynamically update a control

[PATCH 1/2] ALSA: Add snd_ctl_update() to dynamically update a control

[Dimitris Papastamos]

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 make ALSA Mixer cope with this.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
---
 include/sound/control.h |    1 +
 sound/core/control.c    |   44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/include/sound/control.h b/include/sound/control.h
index e67db28..12e4de7 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, int 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..db23745 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -397,6 +397,50 @@ int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
 EXPORT_SYMBOL(snd_ctl_remove);
 
 /**
+ * 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 control instance created via snd_ctl_new() or
+ * snd_ctl_new1() of the given card.
+ *
+ * Returns zero if successful, or a negative error code on failure.
+ *
+ */
+int snd_ctl_update(struct snd_card *card, struct snd_kcontrol *kcontrol,
+		   int add_on_update)
+{
+	struct snd_ctl_elem_id id;
+	struct snd_kcontrol *old;
+	int ret;
+
+	if (!kcontrol)
+		return -EINVAL;
+	if (snd_BUG_ON(!card || !kcontrol->info))
+		return -EINVAL;
+	id = kcontrol->id;
+	down_write(&card->controls_rwsem);
+	old = snd_ctl_find_id(card, &id);
+	if (!old) {
+		up_write(&card->controls_rwsem);
+		if (add_on_update)
+			return snd_ctl_add(card, kcontrol);
+		return -EINVAL;
+	}
+	ret = snd_ctl_remove(card, old);
+	if (ret < 0)
+		return ret;
+	up_write(&card->controls_rwsem);
+	ret = snd_ctl_add(card, kcontrol);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+EXPORT_SYMBOL(snd_ctl_update);
+
+/**
  * snd_ctl_remove_id - remove the control of the given id and release it
  * @card: the card instance
  * @id: the control id to remove
-- 
1.7.4.1

[PATCH 2/2] ASoC: soc-core: Add helper function to handle dynamic update of controls

[Dimitris Papastamos]

This function can be used to update or add controls at runtime.  It will
always try to add a given control if it does not already exist.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
---
 include/sound/soc.h  |    2 ++
 sound/soc/soc-core.c |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index bfa4836..509c1ea 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -344,6 +344,8 @@ struct snd_kcontrol *snd_soc_cnew(const struct snd_kcontrol_new *_template,
 				  const char *prefix);
 int snd_soc_add_controls(struct snd_soc_codec *codec,
 	const struct snd_kcontrol_new *controls, int num_controls);
+int snd_soc_update_controls(struct snd_soc_codec *codec,
+	const struct snd_kcontrol_new *controls, int num_controls);
 int snd_soc_info_enum_double(struct snd_kcontrol *kcontrol,
 	struct snd_ctl_elem_info *uinfo);
 int snd_soc_info_enum_ext(struct snd_kcontrol *kcontrol,
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 17efacd..815103a 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2420,6 +2420,39 @@ int snd_soc_add_controls(struct snd_soc_codec *codec,
 EXPORT_SYMBOL_GPL(snd_soc_add_controls);
 
 /**
+ * snd_soc_update_controls - update an array of controls
+ * Convienience function to update a list of controls.
+ *
+ * @codec: codec to update controls of
+ * @controls: array of controls to update
+ * @num_controls: number of elements in the array
+ *
+ * Return 0 for success, else error.
+ */
+int snd_soc_update_controls(struct snd_soc_codec *codec,
+	const struct snd_kcontrol_new *controls, int num_controls)
+{
+	struct snd_card *card = codec->card->snd_card;
+	int err, i;
+
+	for (i = 0; i < num_controls; i++) {
+		const struct snd_kcontrol_new *control = &controls[i];
+		/* always add on update if not already added */
+		err = snd_ctl_update(card, snd_soc_cnew(control, codec,
+							control->name,
+							codec->name_prefix), 1);
+		if (err < 0) {
+			dev_err(codec->dev, "%s: Failed to update %s: %d\n",
+				codec->name, control->name, err);
+			return err;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_update_controls);
+
+/**
  * snd_soc_info_enum_double - enumerated double mixer info callback
  * @kcontrol: mixer control
  * @uinfo: control element information
-- 
1.7.4.1

Re: [PATCH 1/2] ALSA: Add snd_ctl_update() to dynamically update a control

[Takashi Iwai]

At Tue, 15 Mar 2011 12:21:41 +0000,
Dimitris Papastamos wrote:
> 
> 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 make ALSA Mixer cope with this.
> 
> Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>

The change looks OK to me, but I think the name snd_ctl_update() is
a bit confusing.  It sounds as if it updates its content or such.

I thought of snd_ctl_replace(), but this should take two instances or
so ("replace A with B").  If no better name comes up, I'm fine with
snd_ctl_update().


thanks,

Takashi

> ---
>  include/sound/control.h |    1 +
>  sound/core/control.c    |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 45 insertions(+), 0 deletions(-)
> 
> diff --git a/include/sound/control.h b/include/sound/control.h
> index e67db28..12e4de7 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, int 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..db23745 100644
> --- a/sound/core/control.c
> +++ b/sound/core/control.c
> @@ -397,6 +397,50 @@ int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
>  EXPORT_SYMBOL(snd_ctl_remove);
>  
>  /**
> + * 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 control instance created via snd_ctl_new() or
> + * snd_ctl_new1() of the given card.
> + *
> + * Returns zero if successful, or a negative error code on failure.
> + *
> + */
> +int snd_ctl_update(struct snd_card *card, struct snd_kcontrol *kcontrol,
> +		   int add_on_update)
> +{
> +	struct snd_ctl_elem_id id;
> +	struct snd_kcontrol *old;
> +	int ret;
> +
> +	if (!kcontrol)
> +		return -EINVAL;
> +	if (snd_BUG_ON(!card || !kcontrol->info))
> +		return -EINVAL;
> +	id = kcontrol->id;
> +	down_write(&card->controls_rwsem);
> +	old = snd_ctl_find_id(card, &id);
> +	if (!old) {
> +		up_write(&card->controls_rwsem);
> +		if (add_on_update)
> +			return snd_ctl_add(card, kcontrol);
> +		return -EINVAL;
> +	}
> +	ret = snd_ctl_remove(card, old);
> +	if (ret < 0)
> +		return ret;
> +	up_write(&card->controls_rwsem);
> +	ret = snd_ctl_add(card, kcontrol);
> +	if (ret < 0)
> +		return ret;
> +	return 0;
> +}
> +
> +EXPORT_SYMBOL(snd_ctl_update);
> +
> +/**
>   * snd_ctl_remove_id - remove the control of the given id and release it
>   * @card: the card instance
>   * @id: the control id to remove
> -- 
> 1.7.4.1
>