SD card reader stopped working in kernel 3.6: CONFIG_REGULATOR troubles (solved)

My SD card reader which worked fine with kernel 3.5 stopped working with kernel 3.6 and 3.7. It is a "SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 22)", PCI-ID 0e:06.1

I finally noticed messages like "mmc0: Hardware doesn't report any support voltages." so I tried disabling CONFIG_REGULATOR in kernel config which solved the issue.

Maybe this is also of interest to others. Feel free to contact me if you need more details.