Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Atmel/AT91SAM9G25/HSMCI0/CR#0x0
Control Register
Multi-Media Interface Enable
Multi-Media Interface Disable
Power Save Mode Enable
Power Save Mode Disable
Software Reset
https://github.com/cmsis-svd/cmsis-svd-data