ALSA: hda - Initialize vmaster slave volumes

When the driver is changed to use vmaster or a new slave element is
added by the improvement of the parser code, user may face often the
silent output because of the muted slave mixer although Master volume
is properly set.  And they complain.  And I get upset.

Although such a mixer element should be initialized via "alsactl init",
it'd be more user-friendly if the known output slaves are unmuted and
set to 0dB so that user can control the volume only with Master as
default.  Since Master is still set muted as default even with this
change, no risk of the speaker blow up, too.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 62 insertions, 3 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 0527ae1..0c0ac0e 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -19,6 +19,7 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */
 
+#include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
@@ -2340,6 +2341,56 @@ static int check_slave_present(void *data, struct snd_kcontrol *sctl)
 	return 1;
 }
 
+/* guess the value corresponding to 0dB */
+static int get_kctl_0dB_offset(struct snd_kcontrol *kctl)
+{
+	int _tlv[4];
+	const int *tlv = NULL;
+	int val = -1;
+
+	if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
+		/* FIXME: set_fs() hack for obtaining user-space TLV data */
+		mm_segment_t fs = get_fs();
+		set_fs(get_ds());
+		if (!kctl->tlv.c(kctl, 0, sizeof(_tlv), _tlv))
+			tlv = _tlv;
+		set_fs(fs);
+	} else if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_READ)
+		tlv = kctl->tlv.p;
+	if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE)
+		val = -tlv[2] / tlv[3];
+	return val;
+}
+
+/* call kctl->put with the given value(s) */
+static int put_kctl_with_value(struct snd_kcontrol *kctl, int val)
+{
+	struct snd_ctl_elem_value *ucontrol;
+	ucontrol = kzalloc(sizeof(*ucontrol), GFP_KERNEL);
+	if (!ucontrol)
+		return -ENOMEM;
+	ucontrol->value.integer.value[0] = val;
+	ucontrol->value.integer.value[1] = val;
+	kctl->put(kctl, ucontrol);
+	kfree(ucontrol);
+	return 0;
+}
+
+/* initialize the slave volume with 0dB */
+static int init_slave_0dB(void *data, struct snd_kcontrol *slave)
+{
+	int offset = get_kctl_0dB_offset(slave);
+	if (offset > 0)
+		put_kctl_with_value(slave, offset);
+	return 0;
+}
+
+/* unmute the slave */
+static int init_slave_unmute(void *data, struct snd_kcontrol *slave)
+{
+	return put_kctl_with_value(slave, 1);
+}
+
 /**
  * snd_hda_add_vmaster - create a virtual master control and add slaves
  * @codec: HD-audio codec
@@ -2347,6 +2398,7 @@ static int check_slave_present(void *data, struct snd_kcontrol *sctl)
  * @tlv: TLV data (optional)
  * @slaves: slave control names (optional)
  * @suffix: suffix string to each slave name (optional)
+ * @init_slave_vol: initialize slaves to unmute/0dB
  *
  * Create a virtual master control with the given name.  The TLV data
  * must be either NULL or a valid data.
@@ -2357,9 +2409,9 @@ static int check_slave_present(void *data, struct snd_kcontrol *sctl)
  *
  * This function returns zero if successful or a negative error code.
  */
-int snd_hda_add_vmaster(struct hda_codec *codec, char *name,
+int __snd_hda_add_vmaster(struct hda_codec *codec, char *name,
 			unsigned int *tlv, const char * const *slaves,
-			const char *suffix)
+			const char *suffix, bool init_slave_vol)
 {
 	struct snd_kcontrol *kctl;
 	int err;
@@ -2380,9 +2432,16 @@ int snd_hda_add_vmaster(struct hda_codec *codec, char *name,
 			 (map_slave_func_t)snd_ctl_add_slave, kctl);
 	if (err < 0)
 		return err;
+
+	/* init with master mute & zero volume */
+	put_kctl_with_value(kctl, 0);
+	if (init_slave_vol)
+		map_slaves(codec, slaves, suffix,
+			   tlv ? init_slave_0dB : init_slave_unmute, kctl);
+
 	return 0;
 }
-EXPORT_SYMBOL_HDA(snd_hda_add_vmaster);
+EXPORT_SYMBOL_HDA(__snd_hda_add_vmaster);
 
 /**
  * snd_hda_mixer_amp_switch_info - Info callback for a standard AMP mixer switch