Re: [PATCH] sdio: add MMC_CAP_VDD_165_195 host capability

Philip Langdale
2009-10-10T18:43:22Z

[-- Attachment #1: Type: text/plain, Size: 1230 bytes --]

On Thu, 8 Oct 2009 20:38:26 +0200
Pierre Ossman <pierre@ossman.eu> wrote:

> >
> > In practice, I expect that the timings are close enough that this
> > will work anyway, but I think the situation is analogous to HS-MMC
> > vs HS-SD. There the timings are slightly different and you felt it
> > was enough to justify a separate host cap for each one.
> >
>
> It's difficult to say without seeing the spec. But if things are not
> backwards compatible, then we should probably add either a new timing
> mode, or a new bus mode (where we have open drain and push pull
> today).
>
> > In fact, thinking about it in those terms, it suggests we need to
> > retroactively introduce a reduced-voltage MMC host flag too, just in
> > case SDHCI 3.0 controllers barf on those cards...
> >
>
> Maybe. Again, it's difficult to say without seeing the specifics of
> the new specification.

Make sense. So, I guess the question is do we assume the best case (in
which case there is no additional work to do - the code that is now
in allows low voltage SDIO cards to try and run) or the worst case and
add pre-emptive mode flags?

David, you've actually seen the new spec right? What's your opinion?

--phil

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 197 bytes --]