From 79c7cdd5441f5d3900c1632adcc8cd2bee35c8da Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 9 Feb 2009 14:47:19 +0100 Subject: ALSA: Add kernel-doc comments to vmaster stuff Signed-off-by: Takashi Iwai --- include/sound/control.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'include/sound/control.h') diff --git a/include/sound/control.h b/include/sound/control.h index 4cf8f7aaa13f..ef96f07aa03b 100644 --- a/include/sound/control.h +++ b/include/sound/control.h @@ -176,12 +176,44 @@ int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave, /* optional flags for slave */ #define SND_CTL_SLAVE_NEED_UPDATE (1 << 0) +/** + * snd_ctl_add_slave - Add a virtual slave control + * @master: vmaster element + * @slave: slave element to add + * + * Add a virtual slave control to the given master element created via + * snd_ctl_create_virtual_master() beforehand. + * Returns zero if successful or a negative error code. + * + * All slaves must be the same type (returning the same information + * via info callback). The fucntion doesn't check it, so it's your + * responsibility. + * + * Also, some additional limitations: + * at most two channels, + * logarithmic volume control (dB level) thus no linear volume, + * master can only attenuate the volume without gain + */ static inline int snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave) { return _snd_ctl_add_slave(master, slave, 0); } +/** + * snd_ctl_add_slave_uncached - Add a virtual slave control + * @master: vmaster element + * @slave: slave element to add + * + * Add a virtual slave control to the given master. + * Unlike snd_ctl_add_slave(), the element added via this function + * is supposed to have volatile values, and get callback is called + * at each time quried from the master. + * + * When the control peeks the hardware values directly and the value + * can be changed by other means than the put callback of the element, + * this function should be used to keep the value always up-to-date. + */ static inline int snd_ctl_add_slave_uncached(struct snd_kcontrol *master, struct snd_kcontrol *slave) -- cgit v1.2.3