[PATCH] ide: explain the PCI bus test we do in <asm-i386/ide.h>
Matthew Wilcox asked that this got a comment explaining why it is done so here it is. Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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@ -41,6 +41,12 @@ static __inline__ int ide_default_irq(unsigned long base)
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static __inline__ unsigned long ide_default_io_base(int index)
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{
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/*
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* If PCI is present then it is not safe to poke around
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* the other legacy IDE ports. Only 0x1f0 and 0x170 are
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* defined compatibility mode ports for PCI. A user can
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* override this using ide= but we must default safe.
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*/
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if (pci_find_device(PCI_ANY_ID, PCI_ANY_ID, NULL) == NULL) {
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switch(index) {
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case 2: return 0x1e8;
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