12.1 SDMMC failure when changing speed mode or performing ALL soft reset on-the-fly

Changing speed mode or performing an ALL soft reset while SDCK is active may lead to block the SDMMC.

Work Around

Stop SDCLK before changing speed mode or performing an ALL soft reset, then re-enable SDCLK by writing SDMMC_CCR.SDCLKEN to 0 before writing SDMMC_MC1R/SDMMC_HC1R/SDMMC_HC2R.

Example:

//FIX : stop SDCLK
pSDMMC->SDMMC_CCR = pSDMMC->SDMMC_CCR & ~SDMMC_CCR_SDCLKEN;
switch (speed_mode) {
case DS : pSDMMC->SDMMC_HC1R = pSDMMC->SDMMC_HC1R & ~SDMMC_HC1R_HSEN;
break;
case HS : pSDMMC->SDMMC_HC1R = pSDMMC->SDMMC_HC1R | SDMMC_HC1R_HSEN;
break;
case SDR12 : pSDMMC->SDMMC_HC2R = (pSDMMC->SDMMC_HC2R & ~SDMMC_HC2R_UHSMS_Msk) | SDMMC_HC2R_UHSMS_SDR12;
break;
case SDR25 : pSDMMC->SDMMC_HC2R = (pSDMMC->SDMMC_HC2R & ~SDMMC_HC2R_UHSMS_Msk) | SDMMC_HC2R_UHSMS_SDR25;
break;
case SDR50 : pSDMMC->SDMMC_HC2R = (pSDMMC->SDMMC_HC2R & ~SDMMC_HC2R_UHSMS_Msk) | SDMMC_HC2R_UHSMS_SDR50;
break;
case SDR104 : pSDMMC->SDMMC_HC2R = (pSDMMC->SDMMC_HC2R & ~SDMMC_HC2R_UHSMS_Msk) | SDMMC_HC2R_UHSMS_SDR104;
break;
case DDR50 : pSDMMC->SDMMC_HC2R = (pSDMMC->SDMMC_HC2R & ~SDMMC_HC2R_UHSMS_Msk) | SDMMC_HC2R_UHSMS_DDR50;
break;
}
//FIX : re-start SDCLK
pSDMMC->SDMMC_CCR = pSDMMC->SDMMC_CCR | SDMMC_CCR_SDCLKEN;

Affected Silicon Revisions