linux-kernel - Re: [RFC] enhancing the kernel's graphics subsystem

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Message-Id: <200705220951.24872.jbarnes@virtuousgeek.org>
Date:	Tue, 22 May 2007 09:51:24 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	"Jon Smirl" <jonsmirl@...il.com>
Cc:	"Alan Cox" <alan@...rguk.ukuu.org.uk>,
	"Jeff Garzik" <jeff@...zik.org>,
	"Jesse Barnes" <jesse.barnes@...el.com>,
	linux-kernel@...r.kernel.org,
	"Antonino A. Daplas" <adaplas@...il.com>
Subject: Re: [RFC] enhancing the kernel's graphics subsystem

On Tuesday, May 22, 2007, Jon Smirl wrote:
> On 5/22/07, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> > On Tuesday, May 22, 2007, Jon Smirl wrote:
> > > I've talked to an ATI engineer about VBIOS initialization. The chips
> > > may have different steppings. They flash the right VBIOS that
> > > matches the chip into the ROM on the card.  Given all the various
> > > steppings this is the only sane way to initialize the hardware. I
> > > don't believe generic initialization code that can handle all of the
> > > various steppings exists for any hardware.
> >
> > I think you must have misunderstood.  Last time I worked on ATI, there
> > was a single ROM image that supported several (maybe even all) of
> > their addin cards.  There's nothing magical about them...  But that's
> > beside the point.
>
> What about the poke the obscure value into this undocumented IO port
> class of problem where they are using the chip test interface to work
> around bugs in the silicon.
>
> He also mentioned that all of the OEMs change the standard ROM image
> before loading it onto their cards to handle how they wired things up
> and bugs in other chips.

Right, I think that's where most of the real differences are:  
configuration tables.  And Linux drivers will want to continue to make use 
of those.

> Of course I don't have the source for the ROM so I don't know the
> accuracy of what I was told.

Yeah, it would be nice if we could get the ROM sources, would probably make 
for some interesting (and maybe frightening) reading. :)

Jesse
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