Due to that SoC EDS v17.0 & 17.1 Bootloader code has not been switched to mainstream uboot code, there is no usage information when you run mmc command in uboot command shell. Currently the information is as below:
SOCFPGA_ARRIA10 # mmc
mmc - MMC sub system
The SoC EDS Bootloader can support the MMC commands. The MMC usage information just likes as below:
SOCFPGA_ARRIA10 # mmc
mmc - MMC sub system
Usage:
mmc info - display info of the current MMC device
mmc read addr blk# cnt
mmc write addr blk# cnt
mmc erase blk# cnt
mmc rescan
mmc part - lists available partition on current mmc device
mmc dev [dev] [part] - show or set current mmc device [partition]
mmc list - lists available devices
mmc setdsr <value> - set DSR register value
You can run these commands directly.
The MMC usage information will be added into a future SoC EDS Bootloader version.