> Subject: Re: [PATCH v2] mmc: add option to skip eMMC deinit on OS
> handoff
>
NXP Confidential
> 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]>
Please R-b or A-b.
Thanks,
Peng.
