Intel Graphics question

Joseph Smith joe at
Thu Feb 19 19:11:37 PST 2009

On Fri, 20 Feb 2009 10:19:49 +0800, Zhenyu Wang < at>
> On 2009.02.20 07:43:21 +0800, Joseph Smith wrote:
>> Hello,
>> I am a coreboot ( developer working mostly Intel
>> chipsets. Currently I am working an set-top-box with an Intel chipset. I
> am
>> looking into implementing LVDS and TV-OUT support for various Intel
> GMCH's
>> for set-top-boxes and possibly laptops starting right from the firmware.
> I
>> kind of understand how it works but not exactly sure in which order it
>> needs to happen. Could anyone please help me understand or confirm if
> this
>> is right:
>> 1. All GMCH graphics settings are available through 512k graphics mmio
>> space
>> 2. Current graphics settings are read from graphics mmio space
>> 2. i2c communications is setup through GMCH graphics mmio space
>> 3. LVDS and/or TV-OUT chip is programmed via i2c according to graphic
>> settings read from graphics mmio space
>> 4. DVO port that the LVDS and/or TV-OUT chip is connected to is turned
> on
>> Did I miss anything else?
>> Thanks in advance to any help you can give me.
> MMIO space is where all the modesetting stuffs happen. 
> You can look up xf86-video-intel source for information to setup outputs.
Thanks for the help Zhenyu :-)
I have been looking at the source along with other sources like
i810tvout-0.9.1, nvtv, and the Intel 815 Chipset: Graphics
Controller Programmer’s Reference Manual. Although this is for a newer
chipset than the 815, but that is the only public doc I could find. They
all seem to turn on the DVO port at different points, does that matter?
Can/should the DVO port be turned on before LVDS and/or TV-OUT chip is
programmed or after?

Joseph Smith

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