Re: [PATCH] sdio: add MMC_CAP_VDD_165_195 host capability

Pierre Ossman
2009-09-29T21:37:33Z

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On Tue, 29 Sep 2009 16:20:38 -0400
Philip Langdale <philipl@overt.org> wrote:

>
> My understanding from the previous discussion was that SD 3.0 (and
> presumably
> a matching SDHCI 3.0) fully define the low voltage range. As such, a
> controller
> that is documented to conform to this spec, or is otherwise documented to
> implement the functionality, can be safely allowed to run SD cards that
> also
> claim to support the bit.
>

I must have missed that part of discussion. If the voltage fully
overlaps with the MMC definition, then I don't see the controllers
having to be designed explicitly for SD 3.0. If not, then we probably
need a new voltage bit for the hosts. In that case separating
supporting from non-supporting should sort itself out easily.

> Yes, there is a danger of pre 3.0 cards claiming to suport the low voltage
> range,
> but I think there's a credible chance that no such cards actually exist,
> and if
> they do, I think they're obscure enough to ignore - if they were a problem,
> the
> SD association would have had to abandon using the same bit as MMC uses.
>

Agreed.

Btw, you really need to whip some sense into the line handling of your
email client. :)

Rgds
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-- Pierre Ossman

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