STMicroelectronics STM32 SDMMC Controller

configname: CONFIG_MMC_STM32_SDMMC

Linux Kernel Configuration
└─>Device Drivers
└─>MMC/SD/SDIO card support
└─>STMicroelectronics STM32 SDMMC Controller
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This selects the STMicroelectronics STM32 SDMMC host controller.
If you have a STM32 sdmmc host with internal DMA say Y here.

If unsure, say N.