From 25000c2c8a6cbf9bba2de6560370ee222b4c613d Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 10 Nov 2005 00:10:37 +0100 Subject: [PATCH] ide: explain the PCI bus test we do in Matthew Wilcox asked that this got a comment explaining why it is done so here it is. Signed-off-by: Alan Cox Signed-off-by: Bartlomiej Zolnierkiewicz --- include/asm-i386/ide.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/asm-i386/ide.h b/include/asm-i386/ide.h index 79dfab87135d..454440193eac 100644 --- a/include/asm-i386/ide.h +++ b/include/asm-i386/ide.h @@ -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; -- cgit v1.2.2