The eMMC v4.4 specification defines a 512-byte Extended CSD register that contains eMMC parameters.
Digi has extended the
mmc command with the subcommand
ecsd to access the fields of this register.
=> help mmc
mmc - MMC sub system
... (other subcommands omitted for clarity)
mmc ecsd dump - dump ECSD values
mmc ecsd read offset - read ECSD value at offset
mmc ecsd write offset value - write ECSD value at offset