SDMMC_SDCLK_400KHZ
uint64_t init_freq = SDMMC_SDCLK_400KHZ;
if (freq > SDMMC_SDCLK_400KHZ) {
freq = SDMMC_SDCLK_400KHZ;
case SDMMC_SDCLK_400KHZ:
SDMMC_SDCLK_400KHZ, SDMMC_TIMING_LEGACY);