Re: [PATCH] EmbeddedPkg/MmcDxe: Correct argument of ECSD read

[Leif Lindholm <leif.lindholm@linaro.org>]

On Thu, Jun 29, 2017 at 10:29:08PM +0800, Jun Nie wrote:
> 2017-06-29 20:09 GMT+08:00 Leif Lindholm <leif.lindholm@linaro.org>:
> > On Thu, Jun 29, 2017 at 05:02:05PM +0800, Jun Nie wrote:
> >> The argument of CMD8 should be stuff bits according to standard
> >> JESD84-A44.
> >
> > OK, I realise that "stuff bits" is a term used by the spec, so that is
> > probably sufficient explanation even though the term was known to me.
> > And the MdeModulePkg driver seems to agree on the technical point.
> > My question is why zeroes is the correct "stuff bits" value?
> 
> Yes, it is defined in page 2 in spec. I guess 0 is best filling value
> than other value when we do not need a real value.
> stuff bit: filling 0 bits to ensure fixed length frames for commands
> and responses.

Yeah, fair enough.
It literally is just "nothing".
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

Pushed as 0ad564ffe7.
(Oh, and "Add non-DDR timing mode support" which I had seen as a
companion patch to the ECSD alignment fix also pushed, as 44f4ff6257.)

/
    Leif

> >> Contributed-under: TianoCore Contribution Agreement 1.0
> >> Signed-off-by: Jun Nie <jun.nie@linaro.org>
> >> ---
> >>  EmbeddedPkg/Universal/MmcDxe/MmcIdentification.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/EmbeddedPkg/Universal/MmcDxe/MmcIdentification.c b/EmbeddedPkg/Universal/MmcDxe/MmcIdentification.c
> >> index 4ce0ddd..c28207e 100644
> >> --- a/EmbeddedPkg/Universal/MmcDxe/MmcIdentification.c
> >> +++ b/EmbeddedPkg/Universal/MmcDxe/MmcIdentification.c
> >> @@ -210,7 +210,7 @@ EmmcIdentificationMode (
> >>    }
> >>
> >>    // Fetch ECSD
> >> -  Status = Host->SendCommand (Host, MMC_CMD8, RCA);
> >> +  Status = Host->SendCommand (Host, MMC_CMD8, 0);
> >>    if (EFI_ERROR (Status)) {
> >>      DEBUG ((EFI_D_ERROR, "EmmcIdentificationMode(): ECSD fetch error, Status=%r.\n", Status));
> >>    }
> >> --
> >> 1.9.1
> >>