[alsa-devel] Lost dB volumes on USB headset between 2.6.38 and 3.0

[Raymond Yau]

2011/8/18 Takashi Iwai <tiwai at suse.de>:
> At Tue, 16 Aug 2011 13:31:52 +0100,
> Colin Guthrie wrote:
>>
>> > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
>> > index c04d7c7..cdd19d7 100644
>> > --- a/sound/usb/mixer.c
>> > +++ b/sound/usb/mixer.c
>> > @@ -152,6 +152,7 @@ static inline void check_mapped_dB(const struct usbmix_name_map *p,
>> >     if (p && p->dB) {
>> >             cval->dBmin = p->dB->min;
>> >             cval->dBmax = p->dB->max;
>> > +           cval->initialized = 1;
>> >     }
>> >  }
>> >
>> > @@ -1092,7 +1093,7 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
>> >                             " Switch" : " Volume");
>> >             if (control == UAC_FU_VOLUME) {
>> >                     check_mapped_dB(map, cval);
>> > -                   if (cval->dBmin < cval->dBmax) {
>> > +                   if (cval->dBmin < cval->dBmax || !cval->initialized) {
>> >                             kctl->tlv.c = mixer_vol_tlv;
>> >                             kctl->vd[0].access |=
>> >                                     SNDRV_CTL_ELEM_ACCESS_TLV_READ |
>>
>>
>>
>> Not had a chance to test this yet but I will when I get a moment.
>
> Any chance to test the patch?
>

The patch seem fix the no dB scale problem , however the broken dB
test which you added seem redundant as cval->dBmin and cval->dBmax are
still zero because error in get_min_max() at build_feature_ctl() and
it seem that the valid dBmin and dBMax are calculated by get_min_max()
at mixer_ctl_feature_info() on my usb logitech web cam


LSA endpoint.c:450: 2:3:1: add audio endpoint 0x86
ALSA mixer.c:1182: [5] FU [Mic Capture Switch] ch = 1, val = 0/1/1
ALSA mixer.c:804: 5:2: cannot get min/max values for control 2 (id 5)
ALSA mixer.c:1182: [5] FU [Mic Capture Volume] ch = 1, val = 0/1/1
ALSA mixer.c:804: 5:2: cannot get min/max values for control 2 (id 5)
usbcore: registered new interface driver snd-usb-audio