# # MMC/SD card drivers # comment "MMC/SD Card Drivers" config MMC_BLOCK tristate "MMC block device driver" depends on BLOCK default y help Say Y here to enable the MMC block device driver support. This provides a block device driver, which you can use to mount the filesystem. Almost everyone wishing MMC support should say Y or M here. config MMC_BLOCK_BOUNCE bool "Use bounce buffer for simple hosts" depends on MMC_BLOCK default y help SD/MMC is a high latency protocol where it is crucial to send large requests in order to get high performance. Many controllers, however, are restricted to continuous memory (i.e. they can't do scatter-gather), something the kernel rarely can provide. Say Y here to help these restricted hosts by bouncing requests back and forth from a large buffer. You will get a big performance gain at the cost of up to 64 KiB of physical memory. If unsure, say Y here. config SDIO_UART tristate "SDIO UART/GPS class support" depends on MMC help SDIO function driver for SDIO cards that implements the UART class, as well as the GPS class which appears like a UART.