ALSA: usb-audio - Don't expose broken dB ranges

Some crappy USB-audio devices give broken dB ranges, e.g. both min and max
are 0dB.  This confuses the volume control that prefers dB expression such
as alsactl or PulseAudio.  In such a case, it's much better not to expose
the broken dB information.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2011-04-28 09:58:43 +02:00
Родитель 13eb4ab8ca
Коммит 59bb7f0eeb
1 изменённых файлов: 6 добавлений и 4 удалений

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@ -1097,11 +1097,13 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
append_ctl_name(kctl, control == UAC_FU_MUTE ?
" Switch" : " Volume");
if (control == UAC_FU_VOLUME) {
kctl->tlv.c = mixer_vol_tlv;
kctl->vd[0].access |=
SNDRV_CTL_ELEM_ACCESS_TLV_READ |
SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
check_mapped_dB(map, cval);
if (cval->dBmin < cval->dBmax) {
kctl->tlv.c = mixer_vol_tlv;
kctl->vd[0].access |=
SNDRV_CTL_ELEM_ACCESS_TLV_READ |
SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
}
}
break;