MMC_CS_DONTCARE
host->ios.chip_select = MMC_CS_DONTCARE;
case MMC_CS_DONTCARE:
mmc_set_chip_select(host, MMC_CS_DONTCARE);
host->ios.chip_select = MMC_CS_DONTCARE;
host->ios.chip_select = MMC_CS_DONTCARE;