• Martin Kepplinger's avatar
    ucm2: Librem_5: create a first working profile for the external mic · fa6e1350
    Martin Kepplinger authored
    the settings are all based on a discussion with Charles:
    https://lore.kernel.org/alsa-devel/20220207142129.GB112838@ediswmail.ad.cirrus.com/
    
    Currently we don't get any signal from the external mic. These settings
    result in at least a usable signal (we can try to further improve later).
    
    There are 3 Volume controls for the analog parts, all before the ADC.
    In order from Jack to ADC, they are:
    
    numid=10,iface=MIXER,name='Capture Volume'
       ; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
       : values=63,63
       | dBscale-min=-23.25dB,step=0.75dB,mute=0
    
    "Input PGA Volume Control". 31=0dB. We use 39=+6dB.
    
    numid=7,iface=MIXER,name='MIXINR PGA Volume'
       ; type=INTEGER,access=rw---R--,values=1,min=0,max=7,step=0
       : values=7
       | dBrange-
         rangemin=0,,rangemax=1
           | dBscale-min=0.00dB,step=6.00dB,mute=0
         rangemin=2,,rangemax=2
           | dBscale-min=13.00dB,step=13.00dB,mute=0
         rangemin=3,,rangemax=4
           | dBscale-min=18.00dB,step=2.00dB,mute=0
         rangemin=5,,rangemax=5
           | dBscale-min=24.00dB,step=0.00dB,mute=0
         rangemin=6,,rangemax=7
           | dBscale-min=27.00dB,step=3.00dB,mute=0
    
    "Right input PGA to Right input Boost-Mixer Gain"
    0=0dB. we use 1=+3dB.
    
    numid=8,iface=MIXER,name='MIXINR IN3R Volume'
      ; type=INTEGER,access=rw---R--,values=1,min=0,max=7,step=0
      : values=6
      | dBscale-min=-15.00dB,step=3.00dB,mute=0
    
    we don't use that since we can either route from PGA or IN3R to MIXINR.
    
    ("quotes" are from the datasheet)
    fa6e1350