I'm interested in adding some functionalities to ak4671 codec driver (currently hosted in for-2.6.33 branch). The driver has support for single ended inputs/outputs only, but the actual hardware supports full-differential mode as well. However, the chip doesn't have separate pins for the differential input/outputs, but instead the same pins used in single-ended mode can be reconfigured and reused.

For example: LIN1 and RIN1 inputs (single-ended) can become IN1+/- (differential input), LIN2/RIN2 -> IN2+/-, etc. Similarly for outputs, LOUT1 and ROUT1 (single-ended) can become Mono Receiver RCP/RCN (BTL output), LOUT3/ROUT3 can become Mono Line Output LOP/LON (full-differential). Changing the function of a pin also modifies the audio map:

- Mic Amp Left Mux allow to choose between LIN1, LIN2, LIN3 and LIN4, when pins are configured as single-ended inputs. However, if they are as differential inputs, then the options of Mic Amp Left Mux becomes only IN1+/- and IN3+/-. Similarly for Mic Amp Right Mux: IN2+/- and IN4+/-. - For outputs, single-ended stereo outputs LOUT1/ROUT1, LOUT2/ROUT2 and LOUT3/ROUT3 have separate analog mixers for each channel. But when the output pins work as RCP/RCN or LOP/LON, the output is mono and then each output has a single analog mixer.

My concerns are: - When inputs/outputs are single-ended, then they have its own widgets, i.e.: SND_SOC_DAPM_INPUT("LIN1") SND_SOC_DAPM_INPUT("RIN1") But when they are switched to full-differential mode, they cannot have a separate widget anymore but a single widget instead: SND_SOC_DAPM_INPUT("IN1+/-") Then, it makes me think that input/output widgets cannot be reused in above case. I guess that having the three widgets at the same time is not a safe choice either. - Audio map changes depending on the mode of inputs or outputs, I don't know how the SoC codec driver could handle that.

Any suggestion on what to do in above scenarios?

Thanks, -Misa