Re: [SeaBIOS] Data exchange between coreboot - seabios - option rom

[Kevin O'Connor]

On Wed, Aug 22, 2012 at 04:13:29PM +0200, Christian Gmeiner wrote:
> 2012/8/22 Kevin O'Connor <[e-mail]>:
> > I'm not sure I fully understand your requirements.  Will the board
> > truly have different flat screens hooked up to it?  One can't simply
>
> There are different screens (timing and resolution) connected to the device.
> > compile the EPI info into the BIOS?  Also, if you have to interrogate
> > the display via i2c, can you simply fully generate the EPI info in the
> > vgabios at runtime?
>
> After some time of hacking I came up with the following solution.
>
> 1) Reserve 128 byte in SeaVIDOEBIOS (between ROM haeder and entry points)
> 2) Add all needed epi files to cbfs
> 3) Add possibility to patch vbios during loading based on i2c content
> - see http://review.coreboot.org/#/c/1478/

Why read the i2c and then patch the vgabios - why not just have the
vgabios read from i2c directly?
> 4) Extend vbios to make use of epi/edid data by writing a simple parser
> 5) Extend VBE
> 6) Extend geode code in vbios to make use of parsed epi/edid data

-Kevin

Data exchange between coreboot - seabios - option rom

[Christian Gmeiner]

2012/8/23 Kevin O'Connor <[e-mail]>:
> On Wed, Aug 22, 2012 at 04:13:29PM +0200, Christian Gmeiner wrote:
> > 2012/8/22 Kevin O'Connor <[e-mail]>:
> > > I'm not sure I fully understand your requirements.  Will the board
> > > truly have different flat screens hooked up to it?  One can't simply
> >
> > There are different screens (timing and resolution) connected to the device.
> > > compile the EPI info into the BIOS?  Also, if you have to interrogate
> > > the display via i2c, can you simply fully generate the EPI info in the
> > > vgabios at runtime?
> >
> > After some time of hacking I came up with the following solution.
> >
> > 1) Reserve 128 byte in SeaVIDOEBIOS (between ROM haeder and entry points)
> > 2) Add all needed epi files to cbfs
> > 3) Add possibility to patch vbios during loading based on i2c content
> > - see http://review.coreboot.org/#/c/1478/
>
> Why read the i2c and then patch the vgabios - why not just have the
> vgabios read from i2c directly?

May I need to say that we are talking here about two different i2c buses.
* i2c bus of cs5563
* i2c bus for EDID data transfer - used by VGA

As may panel is connected via LVDS I can not get EDID data from it. So
I want to use
EPI and EDID extension.

So I would read the i2c eeprom at the cs5536 smb bus and get 3 values.
Based on these
values I decide which EDID/EPI binary blob I would like to use.
> > 4) Extend vbios to make use of epi/edid data by writing a simple parser
> > 5) Extend VBE
> > 6) Extend geode code in vbios to make use of parsed epi/edid data
>
> -Kevin