linux-mips
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Re: Configuration of PCI Video card on a BIOS-less board

To: Jun Sun <jsun@mvista.com>, Keith M Wesolowski <wesolows@foobazco.org>
Subject: Re: Configuration of PCI Video card on a BIOS-less board
From: Wayne Gowcher <wgowcher@yahoo.com>
Date: Thu, 10 May 2001 17:19:05 -0700 (PDT)
Cc: Pete Popov <ppopov@mvista.com>, Wayne Gowcher <wgowcher@yahoo.com>, Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>, linux-mips@oss.sgi.com
In-reply-to: <3AFB0FF6.D84A491E@mvista.com>
Sender: owner-linux-mips@oss.sgi.com
Guys,

Sorry for all the confusion, and subsequent traffic as
a result of my mistakes.

I'm still feeling my way with regards to programming
the PCI and have mixed up terms and addresses.

Just for the record :

In actual fact the PCI code is writing physical
addresses to the Base Address Register, eg 0x02000000.
Then later on when the driver is initialising itself
it reads the BAR and adds on KSEG1 :

dev->base_addr = KSEG1ADDR(base_addr);

It is this "dev->base_addr" that gets reported to me
on boot up ( 0xA2000000 ) as being the base address of
the device. The 0xC000 0000 I wrote in my first mail
was from another problem I had been working and was
somehow burned into my brain.

There is nothing like someone questioning one's
assumptions to make one re-evaluate those assumptions.
For this I am grateful to those people, for spotting
the gaping whole of my mistake and bringing it to my
attention. For me at least it has been very useful in
that respect.

I still would like to understand PCI issues more
particularly with respect to so called "legacy PCi
devices" VGA, sound card etc. So if anyone would like
to mail me off the list with tips / reading they have
found useful, it would be most appreciated.

Wayne

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