Use both (enabled by default) DAC1 and DAC2 to provide 2 distinct hardware playback channels. DAC configuration can be accessed through kernel hint - hint.pcm.<unit>.dac="val" with following possible values:
Use both (enabled by default) DAC1 and DAC2 to provide 2
distinct hardware playback channels. DAC configuration can be
accessed through kernel hint - hint.pcm.<unit>.dac="val" with
following possible values:

   0 = Enable both DACs (default)
   1 = Enable single DAC (DAC1)
   2 = Enable single DAC (DAC2)
   3 = Enable both DACs, swap position (DAC2 comes first instead
       of DAC1)

Special case for ES1370:
   Unlike ES1371,2,3/CT5880, volume for each DAC 1 and 2 can be
   controlled indepedently (synth for DAC1, pcm for DAC2). It is
   possible that user will confuse by this behaviour, since both
   DACs are enabled by default. Thus, provide a knob through sysctl
   hw.snd.pcm<unit>.single_pcm_mixer:
     0 = each DACs will be controlled separately (synth/pcm).
     1 = combine both DACs volume mixer controller into a single
         "pcm" (default)
   As a side note, fixed rate operation (provided by previous
   commit) is not a mandatory if the configuration space does not
   involve DAC2 (perhaps disabled by user through the above kernel
   hint). Unlike DAC2, DAC1 has its own register / control space,
   not affected by the speed settings of ADC.

Tested by:	multimedia@
Approved by:	netchild (mentor)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase