Re: MMCv4 support (8-bit support missing)

[Madhusudhan c]

Hi Pierre/Philip,

> I've looked through the MMC 4.2 spec and I see nothing in it that even hints
> that 8-bit support might be optional. So as it stands, the bus testing is still out.
Okay. Its possible that my understanding was wrong in the sense that I
thought bus testing procedure is mandatory to support 8-bit cards. If
8-bit is mandatory for MMC4 cards, then the changes required in the
MMC core to support 8-bit might be  simple. Based on host controller
cap this can be handled.

Philip asked me about the access to the 8-bit controller. We might not
be able to provide you direct access to the hardware platform as it
requires involvement of business managers and so on. But can I be of
help by testing your code on our platform and leting you know the
results?

Regards,
Madhu



On 4/24/07, Pierre Ossman <drzeus@xxxxxxxxx> wrote:
> Madhusudhan c wrote:
> >
> > Suppose a host controller is capable of suporting 8-bit and it tells
> > the core that it can support 8-bit. Now the card that is plugged in
> > might or might not support 8-bit based on the type of the card. There
> > is no field in the ext_csd which will tell you what bus width the card
> > can support.
> >
>
> I've looked through the MMC 4.2 spec and I see nothing in it that even hints
> that 8-bit support might be optional. So as it stands, the bus testing is still out.
>
> Rgds
> Pierre
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