Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Infineon/XMC4300/SDMMC/POWER_CTRL#0x0
SD_BUS_POWER=value1
Power Control Register
SD Bus Power
0 (value1): Power off
1 (value2): Power on
SD Bus Voltage Select
7 (value1): 3.3V (Flattop.)
Hardware reset
https://github.com/cmsis-svd/cmsis-svd-data