From mboxrd@z Thu Jan  1 00:00:00 1970
From: swarren@wwwdotorg.org (Stephen Warren)
Date: Mon, 31 Dec 2012 09:40:11 -0700
Subject: [RFC v1] PCIe support for the Armada 370 and Armada XP SoCs
In-Reply-To: <20121229090955.776816b7@skate>
References: <20121214151045.GA22304@avionic-0098.adnet.avionic-design.de>
 <20121214172729.GA7671@obsidianresearch.com>
 <20121216123340.GB31780@avionic-0098.adnet.avionic-design.de>
 <20121217182911.GA10448@obsidianresearch.com>
 <20121217194147.GA2767@avionic-0098.adnet.avionic-design.de>
 <50CFD0B3.6030208@wwwdotorg.org>
 <20121218025113.GA27029@obsidianresearch.com>
 <50D0A1EA.9090009@wwwdotorg.org>
 <20121220153231.GA11256@avionic-0098.adnet.avionic-design.de>
 <20121222155040.61829b00@skate>
 <20121228210622.GA4519@avionic-0098.adnet.avionic-design.de>
 <20121228221632.3892e90b@skate> <50DE2FFB.8040804@wwwdotorg.org>
 <20121229090955.776816b7@skate>
Message-ID: <50E1BFEB.5070300@wwwdotorg.org>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 12/29/2012 01:09 AM, Thomas Petazzoni wrote:
> Dear Stephen Warren,
> 
> On Fri, 28 Dec 2012 16:49:15 -0700, Stephen Warren wrote:
> 
>>>> That's great. I've been thinking about this some more and one problem
>>>> we'll be facing is that none of the fake host bridges actually exist and
>>>> therefore don't have any official PCI IDs. What I did for Tegra was just
>>>> choose one of the nForce IDs, but that's obviously hackish. One solution
>>>> would be to convince somebody benevolent to sponsor an ID for this
>>>> particular purpose. I think Red Hat did so for Virtio.
>>>
>>> Indeed, that's a remaining problem to solve. Would be great to have
>>> some vendor sponsoring a few IDs for that. At least for a fake PCI Host
>>> Bridge and a fake PCI-to-PCI bridge.
>>
>> Is it actually necessary for a host/PCI bridge to show up on the PCI bus
>> as device 0?
> 
> I don't know, PCI experts are much better placed than me to answer this
> question. How is this related to the problem of PCI IDs ?

If a real PCI device exists, its configuration registers contain the PCI
IDs, so you just "use" them. If no real PCI device exists, yet should,
so you end up implementing a virtual device, the SW needs to decide
which PCI IDs to masquerade as, so you need to come up with some fake IDs.