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ALSA: Add new TLV types for dBwith min/max

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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>
This commit is contained in:
Takashi Iwai
2009-06-16 13:57:07 +02:00
parent 07a2039b8e
commit 085f306541
2 changed files with 20 additions and 2 deletions
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8
sound/core/vmaster.c
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@@ -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;