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Re: Au1500 PCI autoconfig issues with multiple PCI devices?

To: Pete Popov <ppopov@mvista.com>
Subject: Re: Au1500 PCI autoconfig issues with multiple PCI devices?
From: Jun Sun <jsun@mvista.com>
Date: Thu, 24 Apr 2003 18:48:17 -0700
Cc: baitisj@evolution.com, Linux MIPS mailing list <linux-mips@linux-mips.org>, jsun@mvista.com
In-reply-to: <1051215131.511.659.camel@zeus.mvista.com>; from ppopov@mvista.com on Thu, Apr 24, 2003 at 01:12:11PM -0700
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References: <20030424114832.O10148@luca.pas.lab> <20030424121140.G28275@mvista.com> <20030424130459.P10148@luca.pas.lab> <1051215131.511.659.camel@zeus.mvista.com>
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On Thu, Apr 24, 2003 at 01:12:11PM -0700, Pete Popov wrote:
> 
> > Here's another question:
> 
> > What are the goals of the AU1500 PCI auto config? Is it supposed to be a 
> > full
> > implementation, or just enough to work with a PCI card? The reason I ask is
> > that the DBAu1500 has only one PCI slot, so a simple implementation would
> > normally suffice.
> > 
> > Restated: I don't know if the PCI auto config code was designed to work with
> > all sorts of wacky PCI devices. I don't know if the intention of the code 
> > is to
> > support the single PCI slot present on the DbAu1500 development board, or 
> > if it
> > is supposed to be more flexible (and complicated). 
> 
> The MIPS pci auto should work fine with a single PCI bus and it _should_
> be a full implementation. The code was ported from PPC some time ago,
> but sub busses were not tested.  

That is not true.  pciauto has been working P2P bridges pretty much since day 
one.

Usually sub-bus not working is due to type 1 configuration not supported
in pci ops, which is board-dependent code.

I took a brief look of au1x00 pci_ops and it appears it does not support type
1 configuration access.  See arch/mips/ddb5xxx/ddb5477/pci_ops.c for one
example on how type 1 configuration being supported.

Jun

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