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SubjectRe: Linux-2.3.51, and the pre-2.4 series..


On Sat, 11 Mar 2000, Richard Gooch wrote:
> >
> > It's due to the TI cardbus controllers not correctly sensing the
> > power of the inserted card, so the higher level layers will try to
> > apply 5V power and it goes to hell from there. I added code in
> > 2.3.51 to notice when the power sense is wrong and force a new VS
> > sense event.
>
> Argh! Does that mean 5V is being applied to 3V cards and said 3V cards
> are being toasted?

No. The controller has over-voltage protection, so it just means that it
won't work.

The problem is actually due to a unlucky interface between the low-level
slot driver and the card services layer: there's a flag that says "I'm a
3V card", but there is NOT a flag that says "I'm a 5V card". So what
happened here is that
- the cardbus controller did not report any voltages at all.
- the low-level driver thus did not set the 3V flag.
- cardservices thought that "not 3V" == "5V"
- it didn't work.

The fix in 2.3.51 is for the low-level driver to notice that neither the
5V nor the 3V flags were set, and if that happens it will try to force a
re-sense of the card.

I've seen this with the TI1225, and it does not happen with my Ricoh
controller in my Sony VAIO that I did most of the development on. So I
think it's actually a buglet in the TI core.

Linus


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