Messages in this thread | | | Date | Thu, 17 Jul 2003 17:36:25 +0200 (MEST) | From | Geert Uytterhoeven <> | Subject | Re: Fix IDE initialization when we don't probe for interrupts. |
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On Wed, 9 Jul 2003, Linus Torvalds wrote: > On Wed, 9 Jul 2003, Jeff Garzik wrote: > > I'm curious where interrupts are re-enabled, though? > > The low-level drivers seem to do it at every IO. Don't ask me why. But it > gets done automatically by any code that does > > hwif->OUTB(drive->ctl, IDE_CONTROL_REG); > > which is pretty common (just grep for "IDE_CONTROL_REG" and you'll see > what I mean). > > I note that I should have made this "disable irq" be dependent on > IDE_CONTROL_REG being non-zero. Although I don't see when that register > _can_ be zero, it would be a major bummer not to have access to the > control register. > > (Obviously it must be zero for some architecture, though, or those > conditionals woulnd't make sense. Alan? Bartlomiej? What kind of sick > pseudo-IDE controller doesn't have a control register?).
IDE can live without the control register (what do you _really_ need it for?). Hence some hardware doesn't provide it, by leaving out the second bank of 8 IDE registers.
Another trick is the `IDE doubler' for Amiga (but I guess you can make it work on any IDE interface): with a few diodes you can map the second bank of 8 IDE registers to a second IDE chain, doubling the number of devices you can attach.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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