[alsa-devel] [PATCH] ALSA: Add snd_ctl_activate_id()

[Takashi Iwai]

At Wed,  9 Mar 2011 20:03:41 +0000,
Mark Brown wrote:
> 
> From: Takashi Iwai <tiwai at suse.de>
> 
> Added a new API function snd_ctl_activate_id() for activate / inactivate
> the control element dynamically.
> 
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> ---
> 
> You wrote this patch a long time ago now - I'm currently working on a
> driver which I think can make use if it.  Is it OK if I cherry-pick it
> over into my code and push it through the ASoC branch if I do so?  Or
> if you could merge it in the coming merge window, but there's a risk I
> may come up with another way of doing things that doesn't need it.

I'm fine with pulling this from your tree.
This patch was written anyway per Liam's request :)


thanks,

Takashi

> 
>  include/sound/control.h |    2 ++
>  sound/core/control.c    |   46 ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+), 0 deletions(-)
> 
> diff --git a/include/sound/control.h b/include/sound/control.h
> index 7715e6f..e67db28 100644
> --- a/include/sound/control.h
> +++ b/include/sound/control.h
> @@ -115,6 +115,8 @@ 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_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,
> +			int active);
>  struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
>  struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);
>  
> diff --git a/sound/core/control.c b/sound/core/control.c
> index 9ce00ed..db51e4e 100644
> --- a/sound/core/control.c
> +++ b/sound/core/control.c
> @@ -466,6 +466,52 @@ error:
>  }
>  
>  /**
> + * snd_ctl_activate_id - activate/inactivate the control of the given id
> + * @card: the card instance
> + * @id: the control id to activate/inactivate
> + * @active: non-zero to activate
> + *
> + * Finds the control instance with the given id, and activate or
> + * inactivate the control together with notification, if changed.
> + *
> + * Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
> + */
> +int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
> +			int active)
> +{
> +	struct snd_kcontrol *kctl;
> +	struct snd_kcontrol_volatile *vd;
> +	unsigned int index_offset;
> +	int ret;
> +
> +	down_write(&card->controls_rwsem);
> +	kctl = snd_ctl_find_id(card, id);
> +	if (kctl == NULL) {
> +		ret = -ENOENT;
> +		goto unlock;
> +	}
> +	index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
> +	vd = &kctl->vd[index_offset];
> +	ret = 0;
> +	if (active) {
> +		if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
> +			goto unlock;
> +		vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
> +	} else {
> +		if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
> +			goto unlock;
> +		vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
> +	}
> +	ret = 1;
> + unlock:
> +	up_write(&card->controls_rwsem);
> +	if (ret > 0)
> +		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
> +
> +/**
>   * snd_ctl_rename_id - replace the id of a control on the card
>   * @card: the card instance
>   * @src_id: the old id
> -- 
> 1.7.2.3
>