linux-kernel - Re: [PATCH] PCI: Always set prefetchable base/limit upper32 registers

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Message-ID: <20091130235838.GB24539@lackof.org>
Date:	Mon, 30 Nov 2009 16:58:38 -0700
From:	Grant Grundler <grundler@...isc-linux.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Alex Williamson <alex.williamson@...com>, jbarnes@...tuousgeek.org,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: Always set prefetchable base/limit upper32
	registers

On Mon, Nov 30, 2009 at 01:52:03PM -0800, Yinghai Lu wrote:
> if HW state that reg is only 32bit pref,
> why should we care about the upper 32bit?

pref_mem64 describes the resource, not the HW.

All the PCI specs define Type 1 configuration space with Prefetchable Memory
register as 64-bit. Even if the Type 1 (PCI Bridge) HW ignores this register.
See "7.5.3. Type 1 Configuration Space Header" of PCI EXPRESS BASE
SPECIFICATION, REV. 1.1.

> looks like that your bridge device need quirk to clear that so called
> upper 32bit for it.

Hrm...I don't think this is a quirk. PCI spec defines 64-bit PrefMem
window register regardless of what type of resource we program into it.

hth,
grant
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