In message <[EMAIL PROTECTED]> Andrea Campi writes:
: While I was reading your patch I was wondering: what's the situation with
: IRQ sharing between PCCard and other devices? Since you're doing such a
: massive rework, wouldn't this be a good time to also deal with this if
: possible (well not now of course, after your patch is confirmed ok and
: committed)?
Sharing of IRQ between PCCARDs is not possible at the hardware level,
unless your bridge supports it. OLDCARD only supports the legacy
mode, so it isn't possible to share interrupts. NEWCARD supports
cardbus bridges, which support sharing of interrupts in a very limited
sense, but good enough for our purposes.
: In case I was not clear: at the moment pccard and cardbus devices can't
: share IRQ line with any kind of other devices. The best explanation of
: this mentioned only pccard and said it was handled as ISA so you coulnd't
: share, but in theory it was possible to handle pccard in a different way.
: And cardbus shouldn't be a problem at all I think.
ISA bus cannot share interrupts at all. Full stop[*]. Most
pccard/cardbus bridges operate in a mode where they use ISA
interrupts, so cannot share interrupts at all. The hardware just
won't work if you try. NEWCARD tries to kick the cardbus bridge into
full PCI mode, where you can share interrupts, since all the
interrupts are going through the PCI hardware chain which does support
interrupt sharing.
Warner
[*] Special, oddball cards can be made to support sharing. Those
aren't relevant here because pcic bridges and the like aren't oddball.
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