[U-Boot] [PATCH] mmc: support hs400 enhanced strobe mode

[Peng Fan]

Hi Fabio,
> 
> Hi Peng,
> 
> On Mon, Apr 15, 2019 at 10:33 PM Peng Fan <peng.fan at nxp.com> wrote:
> >
> > eMMC 5.1+ supports HS400 Enhances Strobe mode without the need for
> > tuning procedure.
> > The flow is as following:
> >  - set HS_TIMIMG (Highspeed)
> >  - Host change freq to <= 52Mhz
> >  - set the bus width to Enhanced strobe and DDR8Bit(CMD6),
> >    EXT_CSD[183] = 0x86 instead of 0x80
> >  - set HS_TIMING to 0x3 (HS400)
> >  - Host change freq to <= 200Mhz
> >  - Host select HS400 enhanced strobe complete
> >
> > Signed-off-by: Peng Fan <peng.fan at nxp.com>
> > ---
> >
> > This is actually a resend of
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatc
> >
> hwork.ozlabs.org%2Fpatch%2F1018188%2F&data=02%7C01%7Cpeng.fa
> n%40nx
> >
> p.com%7C49da3f56664f4651249e08d6c20c0a55%7C686ea1d3bc2b4c6fa92c
> d99c5c3
> >
> 01635%7C0%7C0%7C636909754297976230&sdata=ENHPWHJbIZYQPgB
> 92hbNTROiA
> > TEML7yYJMNGxHwtHkw%3D&reserved=0
> > which got no response.
> > Rebased on master.
> >
> >
> >  drivers/mmc/Kconfig      | 12 ++++++++
> >  drivers/mmc/mmc-uclass.c | 15 +++++++++
> >  drivers/mmc/mmc.c        | 79
> +++++++++++++++++++++++++++++++++++++++++++++++-
> >  include/mmc.h            | 15 +++++++++
> >  4 files changed, 120 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig index
> > 04a4e7716f..3ef7580a43 100644
> > --- a/drivers/mmc/Kconfig
> > +++ b/drivers/mmc/Kconfig
> > @@ -111,6 +111,18 @@ config SPL_MMC_UHS_SUPPORT
> >           cards. The IO voltage must be switchable from 3.3v to 1.8v.
> The bus
> >           frequency can go up to 208MHz (SDR104)
> >
> > +config MMC_HS400_ES_SUPPORT
> > +       bool "enable HS400 Enhanced Strobe support"
> > +       help
> > +         The HS400 Enhanced Strobe mode is support by some eMMC.
> The bus frequency is up to
> > +         200MHz. This mode does not tune the IO.
> 
> Is there any board that can select this option?

This patch is just a resend which
got no response since first posted in 2018/12.

The support on i.MX8 will be posted, if there is no major comments on
the common code part.

Thanks,
Peng.

> 
> Otherwise it will be just dead code.
> 
> Thanks