From f5b1db634280ecaf3147ee996f26aad0ed4828c4 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 16 Jan 2009 18:15:22 +0100 Subject: ALSA: add snd_ctl_add_slave_uncached() Added snd_ctl_add_slave_uncached() function to add a slave element with volatile controls. The values of normal slave elements are supposed to be cachable, i.e. they are changed only via the put callbacks. OTOH, when a slave element is volatile and its values may be changed by other reason (e.g. hardware status change), the values will get inconsistent. The new function allows the slave elements with volatile changes. When the slave is tied with this call, the native get callback is issued at each time so that the values are always updated. Signed-off-by: Takashi Iwai --- include/sound/control.h | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'include/sound') diff --git a/include/sound/control.h b/include/sound/control.h index 4721b4bba05..4cf8f7aaa13 100644 --- a/include/sound/control.h +++ b/include/sound/control.h @@ -171,6 +171,22 @@ int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol, */ struct snd_kcontrol *snd_ctl_make_virtual_master(char *name, const unsigned int *tlv); -int snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave); - +int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave, + unsigned int flags); +/* optional flags for slave */ +#define SND_CTL_SLAVE_NEED_UPDATE (1 << 0) + +static inline int +snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave) +{ + return _snd_ctl_add_slave(master, slave, 0); +} + +static inline int +snd_ctl_add_slave_uncached(struct snd_kcontrol *master, + struct snd_kcontrol *slave) +{ + return _snd_ctl_add_slave(master, slave, SND_CTL_SLAVE_NEED_UPDATE); +} + #endif /* __SOUND_CONTROL_H */ -- cgit v1.2.3 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') diff --git a/include/sound/control.h b/include/sound/control.h index 4cf8f7aaa13..ef96f07aa03 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