In analog loopback mode, DACs should not be enabled. For that reason, DAC widgets (DAC Right1, DAC Left1, DAC Right2, DAC Left2) will power DACs only during playback.
Analog loopback requires to set a master enable bit when any of the analog bypass switches are enabled.
I have also noticed this, also in analog loopback mode the bits in the OPTION register can be cleared, since we don't need those to have analog loopback.
At least, the digital filters (configured in OPTION reg) are enabled when the corresponding DAC is enabled, can we attach them to a DAC somehow? Could it be a valid approach?
But I'm afraid, this patch does break the Digital loopback, which needs the DACs to be powered, in case when the capture path is set in analog mode the ADC(s) also need to be powered.
I think that digital loopback should mix TX with RX only when both digital paths are enabled, i.e. in a full-duplex scenario. I don't expect it to automatically enable DACs for me, although maybe I'm wrong and my argument breaks what digital loopback means :( Please clarify.
Both analog and digital loopback connects to 'Analog XY Playback Mixer', which turns on/off the physical DAC on the given route.
That was a part of the audio map that doesn't make much sense to me, joining analog and digital loopback.
I have been thinking of - as a part of a big clean up - to separate these, since as you have pointed out, the DACs are not needed for the analog loopback.