-----Original Message-----
From: One Thousand Gnomes [mailto:gnomes at lxorguk.ukuu.org.uk]
Sent: 09 November 2016 13:55
To: Arnd Bergmann
Cc: Mark Rutland; Yuanzhichang; catalin.marinas at arm.com;
will.deacon at arm.com; robh+dt at kernel.org; bhelgaas at google.com;
olof at lixom.net; linux-arm-kernel at lists.infradead.org;
lorenzo.pieralisi at arm.com; linux-kernel at vger.kernel.org; Linuxarm;
devicetree at vger.kernel.org; linux-pci at vger.kernel.org; linux-
serial at vger.kernel.org; minyard at acm.org; benh at kernel.crashing.org;
liviu.dudau at arm.com; zourongrong at gmail.com; John Garry; Gabriele
Paoloni; zhichang.yuan02 at gmail.com; kantyzc at 163.com; xuwei (O);
marc.zyngier at arm.com
Subject: Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for
special ISA

quoted

I think it is a relatively safe assumption that there is only one
ISA bridge. A lot of old drivers hardcode PIO or memory addresses

It's not a safe assumption for x86 at least. There are a few systems
with
multiple ISA busses particularly older laptops with a docking station.

Mmmm right...now the point is that this kind of special devices appearing
as a special ISA bus will probably never appear on x86 platforms (I guess).

So maybe it is a safe assumption because of this...?

Thanks

Gab

quoted

when talking to an ISA device, so having multiple instances is
already problematic.

PCMCIA devices handle it themselves so are ok. I'm not clear how the
dual
PIIX4 configuration used in the older IBM laptop docks actually worked
so
I assume the transaction went out of both bridges and providing one of
them responded the other kept silent as you simply stuffed the card
into
the dock and it worked.

Alan