For me, this fixes a problem with using eMMC storage in MMCCAM configuration with dwmmc driver (on Rock64). The problem appeared after commit 07da3bb5d56c85 "mmc: support for SPI bus type". The problem was caused by the said commit changing the layout of struct mmc_ios which is embedded into struct ccb_trans_settings_mmc with the latter being embedded into struct ccb_trans_settings, a member of union ccb. The layout mattered for two reasons: 1. dwmmc sets cmd.error only in case of an error; 2. mmc_da's sdda_start_init uses the same ccb for different transaction types without explicitly clearing the object between transactions. As a result, cmd.error could start out with a non-zero value and dwmmc would keep that value which would then be interpreted as a failure. Such a failure happened in mmc_set_timing resulting in incorrect timing settings and subsequent complete failure to communicate with the eMMC module. Reviewed by: pkelsey (cherry picked from commit 10db2ad8614adc544292856c693503ca8e9c9fd9)