On 24-08-2026 08:30, 박민우 (MW Park) wrote:
When U-Boot hands off to the OS, mmc_deinit() renegotiates the bus down out of HS200/HS400 by issuing CMD6 switches, then changes the clock; see commit fceea9926804 ("mmc: Downgrade SD/MMC from UHS/HS200/HS400 modes before boot") for the original motivation. For eMMC this downgrade is unnecessary when the OS re-initialises the device itself: CMD0 returns the protocol state machine to Idle, and the OS renegotiates from scratch regardless of the mode U-Boot left the device in.Add a Kconfig option, MMC_SKIP_EMMC_DEINIT, to skip this downgrade for eMMC devices. SD cards are always deinitialized, keeping the conservative default behaviour. This removes unnecessary CMD6 switches and clock changes from the OS-handoff path, which matters on fast-boot / automotive platforms. Signed-off-by: Minwoo Park<[email protected]>
Signed-off-by: Tanmay Kathpalia <[email protected]>
