Commit 25000c2c authored by Alan Cox's avatar Alan Cox Committed by Bartlomiej Zolnierkiewicz

[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: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
parent f5b2d8b4
......@@ -41,6 +41,12 @@ static __inline__ int ide_default_irq(unsigned long base)
static __inline__ unsigned long ide_default_io_base(int index)
{
/*
* If PCI is present then it is not safe to poke around
* the other legacy IDE ports. Only 0x1f0 and 0x170 are
* defined compatibility mode ports for PCI. A user can
* override this using ide= but we must default safe.
*/
if (pci_find_device(PCI_ANY_ID, PCI_ANY_ID, NULL) == NULL) {
switch(index) {
case 2: return 0x1e8;
......
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