SEL_MADC_MCPC necessary?

Hello,

I have a rev. B beagle-xm and I can read out the MADC voltage levels under
/sys/devices/platform/twl4030_madc_hwmon without problem

what puzzles me is that SEL_MADC_MCPC in the CARKIT_ANA_CTRL register of the TPS65950 PMIC is NOT set, and I still can read meaningful values

on a similar board (but with a different revision of the TPS65950) I can NOT get reasonable MADC voltage levels (they are always close to zero);
however, this second board works as soon as I set SEL_MADC_MCPC (i.e. I can read voltages from ADCIN3 to ADCIN6)

as far as I understand the TRM of the TPS65950, SEL_MADC_MCPC should be set

is this a known issue of the TPS65950?
I tried to look up errata, but found no matching issue on record

my beagle-xm rev. B has a TPS65950B E1, the other PMIC is marked TPS65950A3 G1

thanks, regards, p.