Changeset 426 for GPL/trunk/alsa-kernel/include/sound/control.h

Timestamp:

May 9, 2009, 11:45:26 AM (16 years ago)

Author:

Paul Smedley

Message:

Update alsa-kernel to ALSA 1.0.20 level

File:

• GPL/trunk/alsa-kernel/include/sound/control.h (modified) (2 diffs)

GPL/trunk/alsa-kernel/include/sound/control.h

@@ -184 +184 @@
 #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)
@@ -190 +208 @@
 }
 
+/**
+ * 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,