[alsa-devel] [PATCH 1/2 v2] ALSA: Add snd_ctl_update() to dynamically update a control
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 | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 47 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..9c5d7a9 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -397,6 +397,52 @@ 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) { + up_write(&card->controls_rwsem); + 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
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
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.
- Updates the control instance created via snd_ctl_new() or
- snd_ctl_new1() of the given card.
This description was copied from snd_ctl_add(), and the "created ..." part isn't really useful here.
It should be mentioned that the old control is destroyed, because some drivers store volatile state in the control's private_data/_value, or keep a pointer to the control('s ID) to be able to call snd_ctl_notify() for it later.
- Returns zero if successful, or a negative error code on failure.
superfluous empty line
+int snd_ctl_update(struct snd_card *card, struct snd_kcontrol *kcontrol,
int add_on_update)
add_on_update should be bool
- up_write(&card->controls_rwsem);
- ret = snd_ctl_add(card, kcontrol);
Doing this outside the semaphore doesn't look good.
I wonder whether snd_ctl_add() is the right function to use, because it will assign a different numid event if the control didn't change.
A separate patch needs to be made to make ALSA Mixer cope with this.
What happens?
Regards, Clemens
At Tue, 15 Mar 2011 15:17:58 +0100, Clemens Ladisch wrote:
- up_write(&card->controls_rwsem);
- ret = snd_ctl_add(card, kcontrol);
Doing this outside the semaphore doesn't look good.
Using an internal function without semaphore would be preferred, yes.
I wonder whether snd_ctl_add() is the right function to use, because it will assign a different numid event if the control didn't change.
Hm, actually the function can compare whether it's really changed or not. If any change, it makes really sense to assign a different numid.
Takashi
2011/3/15 Takashi Iwai tiwai@suse.de
At Tue, 15 Mar 2011 15:17:58 +0100, Clemens Ladisch wrote:
- up_write(&card->controls_rwsem);
- ret = snd_ctl_add(card, kcontrol);
Doing this outside the semaphore doesn't look good.
Using an internal function without semaphore would be preferred, yes.
I wonder whether snd_ctl_add() is the right function to use, because it will assign a different numid event if the control didn't change.
Hm, actually the function can compare whether it's really changed or not. If any change, it makes really sense to assign a different numid.
does it mean that the driver can update "Input Source" controls for those HDA codec on a motherboard with 3 audio jacks at rear panel ?
i.e. remove/add "Rear Mic" and "Line in" from/to "Input Source" when user switch "channel_mode" between 2 and 6 or switch"smart51" on/off
At Wed, 16 Mar 2011 08:56:36 +0800, Raymond Yau wrote:
2011/3/15 Takashi Iwai tiwai@suse.de
At Tue, 15 Mar 2011 15:17:58 +0100, Clemens Ladisch wrote:
- up_write(&card->controls_rwsem);
- ret = snd_ctl_add(card, kcontrol);
Doing this outside the semaphore doesn't look good.
Using an internal function without semaphore would be preferred, yes.
I wonder whether snd_ctl_add() is the right function to use, because it will assign a different numid event if the control didn't change.
Hm, actually the function can compare whether it's really changed or not. If any change, it makes really sense to assign a different numid.
does it mean that the driver can update "Input Source" controls for those HDA codec on a motherboard with 3 audio jacks at rear panel ?
i.e. remove/add "Rear Mic" and "Line in" from/to "Input Source" when user switch "channel_mode" between 2 and 6 or switch"smart51" on/off
In theory, yes. But, practically, I'm afraid that this is rather confusing for normal desktop apps. Most of mixer apps aren't written robustly for handling the dynamically changed control elements.
Takashi
On Tue, Mar 15, 2011 at 03:17:58PM +0100, Clemens Ladisch wrote:
Doing this outside the semaphore doesn't look good.
Yes, I was thinking about the same thing, wasn't sure about nesting rw semaphores though.
I wonder whether snd_ctl_add() is the right function to use, because it will assign a different numid event if the control didn't change.
Hm, indeed. I can probably inline a slightly different version of snd_ctl_add()?
A separate patch needs to be made to make ALSA Mixer cope with this.
What happens?
It doesn't break or anything hopefully. It will probably need support for handling the update of the controls (without exiting and starting it again). I've only tested it against alsa-utils 1.0.20 and it worked fine with a few changes (updating the controls on the fly).
Thanks, Dimitris
2011/3/16 Dimitris Papastamos dp@opensource.wolfsonmicro.com
On Tue, Mar 15, 2011 at 03:17:58PM +0100, Clemens Ladisch wrote:
A separate patch needs to be made to make ALSA Mixer cope with this.
What happens?
It doesn't break or anything hopefully. It will probably need support for handling the update of the controls (without exiting and starting it again). I've only tested it against alsa-utils 1.0.20 and it worked fine with a few changes (updating the controls on the fly).
It depend on how the driver update control, since snd_mixer_selem just combine "volume" and "switch" controls of same name into a single selem
if the driver just change the name of volume control, I guess alsamixer still need to reload the mixer
participants (4)
-
Clemens Ladisch -
Dimitris Papastamos -
Raymond Yau -
Takashi Iwai