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authorTakashi Iwai <tiwai@suse.de>2011-04-28 09:58:43 +0200
committerTakashi Iwai <tiwai@suse.de>2011-04-28 09:58:43 +0200
commit59bb7f0eebe69aa32a5c7917a23a7da1c5667d73 (patch)
tree07148368f34290c5127f106909b1fb2422a3f7fb /sound/usb
parent13eb4ab8ca719c852ae5fbd6e803afa333ad569a (diff)
downloadlinux-linaro-precise-59bb7f0eebe69aa32a5c7917a23a7da1c5667d73.tar.gz
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>
Diffstat (limited to 'sound/usb')
-rw-r--r--sound/usb/mixer.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 5e477571660..c8c28cd7553 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -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;