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ASoC: core: Support for limiting the volume

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Add support for the core to limit the maximum volume on an
existing control.
The function will modify the soc_mixer_control.max value
of the given control.
The new value must be lower than the original one (chip maximum)

If there is a need for limiting a gain on a given control,
than machine drivers can do the following in their
snd_soc_dai_link.init function:

snd_soc_limit_volume(codec, "TPA6140A2 Headphone Playback Volume", 21);

This will modify the original 31 (chip maximum) to 21, so user
space will not be able to set the gain higher than this.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
This commit is contained in:
Peter Ujfalusi 2010-05-07 14:05:49 +03:00 committed by Mark Brown
parent 3057876498
commit 637d3847ba
2 changed files with 41 additions and 0 deletions
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2
include/sound/soc.h
View File

@ -326,6 +326,8 @@ int snd_soc_get_volsw_s8(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_value *ucontrol);
int snd_soc_put_volsw_s8(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_value *ucontrol);
int snd_soc_limit_volume(struct snd_soc_codec *codec,
const char *name, int max);
/**
* struct snd_soc_jack_pin - Describes a pin to update based on jack detection

39
sound/soc/soc-core.c
View File

@ -2237,6 +2237,45 @@ int snd_soc_put_volsw_s8(struct snd_kcontrol *kcontrol,
}
EXPORT_SYMBOL_GPL(snd_soc_put_volsw_s8);
/**
* snd_soc_limit_volume - Set new limit to an existing volume control.
*
* @codec: where to look for the control
* @name: Name of the control
* @max: new maximum limit
*
* Return 0 for success, else error.
*/
int snd_soc_limit_volume(struct snd_soc_codec *codec,
const char *name, int max)
{
struct snd_card *card = codec->card;
struct snd_kcontrol *kctl;
struct soc_mixer_control *mc;
int found = 0;
int ret = -EINVAL;
/* Sanity check for name and max */
if (unlikely(!name || max <= 0))
return -EINVAL;
list_for_each_entry(kctl, &card->controls, list) {
if (!strncmp(kctl->id.name, name, sizeof(kctl->id.name))) {
found = 1;
break;
}
}
if (found) {
mc = (struct soc_mixer_control *)kctl->private_value;
if (max <= mc->max) {
mc->max = max;
ret = 0;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(snd_soc_limit_volume);
/**
* snd_soc_dai_set_sysclk - configure DAI system or master clock.
* @dai: DAI