[alsa-devel] snd_usb_audio - siberia elite prism soundcard issues

[Raymond Yau]

>> >> >> >> > >
>> >> >> >> > > > amixer: Control hw:2 element read error: Invalid argument
>> >> >> >> > > > usb 1-1.3: 10:0: cannot get min/max values for control 3
(id 10)
>> >> >> >> > > > usb 1-1.3: 2:1: cannot get freq at ep 0x1
>> >> >>
>> >> >> numid=5,iface=MIXER,name='PCM Volume' ;
type=INTEGER,access=rw------,values=2,min=0,max=1,step=0 amixer: Control
hw:2 element read error: Invalid argument
>> >> >>
>> >> >> numid=6,iface=MIXER,name='PCM Volume',index=1 ;
type=INTEGER,access=rw------,values=1,min=0,max=1,step=0 amixer: Control
hw:2 element read error: Invalid argument
>> >> >>
>> >> >> numid=7,iface=MIXER,name='PCM Volume',index=2 ;
type=INTEGER,access=rw------,values=1,min=0,max=1,step=0 amixer: Control
hw:2 element read error: Invalid argument
>> >> >>
>> >> >> numid=8,iface=MIXER,name='PCM Volume',index=3 ;
type=INTEGER,access=rw------,values=1,min=0,max=1,step=0 amixer: Control
hw:2 element read error: Invalid argument
>> >> >>
>> >> >> numid=9,iface=MIXER,name='PCM Volume',index=4 ;
type=INTEGER,access=rw------,values=1,min=0,max=1,step=0 amixer: Control
hw:2 element read error: Invalid argument
>> >> >>

>
> In case this can be of any useful info, in the form of unknown controls
reported by the lsusb output, manufacturer software in other OS has
controls for:
>
> * dolby surround activation (off and on).
> * microphone input volume (which works fine now) in snd_usb_audio
> * microphone input "compression" (supposedly to keep input within certain
non distorting levels)
> * input noise reduction (off and on too)
> * micro retro feedback volume
> * equalizer.

You need to find out the terminals of two inputs if you want to know the
function of this mixer unit

> bUnitID 10
> bNrInPins 2
> baSourceID( 0) 9
> baSourceID( 1) 1

There are debug output in the system log when you compiled the driver with
debug option

usb_audio_dbg(state->chip, "[%d] MU [%s] ch = %d, val = %d/%d\n",
    cval->head.id, kctl->id.name, cval->channels, cval->min, cval->max);

Is the suffix "Volume" correct since it may be just a mute switch ?

3.13.4 Mixer Unit
The Mixer Unit (MU) transforms a number of logical input channels into a
number of logical output channels. The input channels are grouped into one
or more audio channel clusters. Each cluster enters the Mixer Unit through
an Input Pin. The logical output channels are grouped into one audio
channel cluster and leave the Mixer Unit through a single Output Pin. Every
input channel can virtually be mixed into all of the output channels. If n
is the total number of input ixer channels and m is the number of output
channels, then there is a two-dimensional array (n · m) of M Controls in
the Mixer Unit.

Not all of these Controls have to be physically implemented. Some Controls
can have a fixed setting and be non-programmable.

The Mixer Unit Descriptor reports which Controls are programmable in the
bmControls bitmap field. Using this model, a permanent connection can be
implemente d by reporting the Control as non-programmable in the bmControls
bitmap and by returning a nnection can be implemented by Control setting of
0 dB when requested. Likewise, a missing (muting) co reporting the Control
as non-programmable in the bmControls bitmap and by returning a Control
setting of –∞ dB. A Mixer Unit MUST respond to the appropriate Get Request
to allow the Host to retrieve the actual settings on each of the (n · m)
Mixer Controls.

4.7.2.6 Mixer Unit Descriptor

The bmMixerControls field stores the bit array row after row where the MSb
of the first byte corresponds to the connection between input channel 1 and
output channel 1. If (n · m) is not an integer multiple of 8, the bit array
is padded with zeros until an integer number of bytes is occupied.

The number of bytes used to store the bit array, N, can be calculated as
follows:
IF ((n * m) MOD 8) <> 0 THEN
N = ((n * m) DIV 8) + 1
ELSE
N = ((n * m) DIV 8)

The bmControls field contains a set of bit pairs, indicating which Controls
are present and what their capabilities are.  If a Control is present, it
must be Host readable. If a certain Control is not present then the bit
pair must be set to 0b00. If a Control is present but read-only, the bit
pair must be set to 0b01. If a Control is also Host programmable, the bit
pair must be set to 0b11. The value 0b10 is not allowed.

For uac2

At location 11 + p + N

D1..0: Cluster Control
D3..2: Underflow Control
D5..4: Overflow Control
D7..6: Reserved. Must be set to 0.

static void build_mixer_unit_ctl(struct mixer_build *state,
struct uac_mixer_unit_descriptor *desc,
int in_pin, int in_ch, int unitid,
struct usb_audio_term *iterm)
{
struct usb_mixer_elem_info *cval;
unsigned int num_outs = uac_mixer_unit_bNrChannels(desc);
unsigned int i, len;
struct snd_kcontrol *kctl;
const struct usbmix_name_map *map;

map = find_map(state, unitid, 0);
if (check_ignored_ctl(map))
return;

cval = kzalloc(sizeof(*cval), GFP_KERNEL);
if (!cval)
return;

snd_usb_mixer_elem_init_std(&cval->head, state->mixer, unitid);
cval->control = in_ch + 1; /* based on 1 */
cval->val_type = USB_MIXER_S16;
for (i = 0; i < num_outs; i++) {
__u8 *c = uac_mixer_unit_bmControls(desc, state->mixer->protocol);

if (check_matrix_bitmap(c, in_ch, i, num_outs)) {
cval->cmask |= (1 << i);
cval->channels++;
}
}

/* get min/max values */
get_min_max(cval, 0);

kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);
if (!kctl) {
usb_audio_err(state->chip, "cannot malloc kcontrol\n");
kfree(cval);
return;
}
kctl->private_free = snd_usb_mixer_elem_free;

len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));
if (!len)
len = get_term_name(state, iterm, kctl->id.name,
    sizeof(kctl->id.name), 0);
if (!len)
len = sprintf(kctl->id.name, "Mixer Source %d", in_ch + 1);
append_ctl_name(kctl, " Volume");

usb_audio_dbg(state->chip, "[%d] MU [%s] ch = %d, val = %d/%d\n",
    cval->head.id, kctl->id.name, cval->channels, cval->min, cval->max);
snd_usb_mixer_add_control(&cval->head, kctl);
}