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SubjectRE: [patch] split MMC_CAP_4_BIT_DATA


I'd like to say something about this issue.
Currently,the blackfin on chip SD host ONLY support 1-bit MMC while
support 1-bit/4-bit SD/SDIO.
And we want our driver to support both 1-bit MMC and 4-bit SD/SDIO.but
the current MMC driver framework
Only allow us to set one kind of bus width,either 1-bit or 4-bit.So in
order to meet our case,we need more flexible mechanism
To inform the upper commom driver to know our situation.


-----Original Message-----
From: Bryan Wu []
Sent: Wednesday, January 09, 2008 10:33 AM
To: Pierre Ossman;
Cc: Mike Frysinger;
Subject: Re: [patch] split MMC_CAP_4_BIT_DATA

On Jan 9, 2008 4:49 AM, Pierre Ossman <> wrote:
> On Tue, 8 Jan 2008 14:40:49 -0500
> Mike Frysinger <> wrote:
> >
> > i dont understand what's confusing. the Blackfin on chip host
> > controller only supports 1-bit MMC, but it supports 4-bit SD/SDIO.
> > this is a fact. while it may be a stupid decision, it is what it
> > is, and i need the framework made more flexible in order to get the
> > Blackfin driver merged cleanly. we do software for hardware, we
dont do hardware.
> Well, since I've seen no _hardware_ differences between 4-bit MMC and
4-bit SD, "support" in this case must me "vendor will guarantee it
works". And that is not the kind of "support" that needs a distinction
in the code.
> So, again, if you feel that there is a hardware difference between
4-bit MMC and 4-bit SD then please elaborate as it is my understanding
that they are identical.

As Mike said, the reason split this flag is because Blackfin on-chip
SDIO controller's limitation.
Cliff is working on it for a long time, so I dropped him in. Hope he can
clarify the confusing things.

-Bryan Wu

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