ALSA: Add new TLV types for dBwith min/max

Add new types for TLV dB scale specified with min/max values instead
of min/step since the resolution can't match always with the one
a device provides.  For example, usb audio devices give 1/256 dB
resolution while ALSA TLV is based on 1/100 dB resolution.
The new min/max types have less problems because the possible
rounding error happens only at min/max.

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

1 files changed, 6 insertions, 2 deletions

diff --git a/sound/core/vmaster.c b/sound/core/vmaster.c
index 257624bd1997..3b9b550109cb 100644
--- a/sound/core/vmaster.c
+++ b/sound/core/vmaster.c
@@ -353,7 +353,8 @@ static void master_free(struct snd_kcontrol *kcontrol)
  *
  * The optional argument @tlv can be used to specify the TLV information
  * for dB scale of the master control.  It should be a single element
- * with #SNDRV_CTL_TLVT_DB_SCALE type, and should be the max 0dB.
+ * with #SNDRV_CTL_TLVT_DB_SCALE, #SNDRV_CTL_TLV_DB_MINMAX or
+ * #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.
  */
 struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
                                                  const unsigned int *tlv)
@@ -384,7 +385,10 @@ struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
         kctl->private_free = master_free;
 
         /* additional (constant) TLV read */
-        if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE) {
+        if (tlv &&
+            (tlv[0] == SNDRV_CTL_TLVT_DB_SCALE ||
+             tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX ||
+             tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX_MUTE)) {
                 kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
                 memcpy(master->tlv, tlv, sizeof(master->tlv));
                 kctl->tlv.p = master->tlv;