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

[Kevin O'Connor]

On Thu, Aug 23, 2012 at 08:54:08AM +0200, Christian Gmeiner wrote:
> 2012/8/23 Kevin O'Connor :
> > 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.

So, why not read the i2c eeprom directly from the vgabios?  It seems
fragile to build an interface between coreboot and a vgabios just so
coreboot can read the eeprom.

-Kevin

Data exchange between coreboot - seabios - option rom

[Christian Gmeiner]

2012/8/23 Kevin O'Connor :
> On Thu, Aug 23, 2012 at 08:54:08AM +0200, Christian Gmeiner wrote:
> > 2012/8/23 Kevin O'Connor :
> > > 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.
>
> So, why not read the i2c eeprom directly from the vgabios?  It seems
> fragile to build an interface between coreboot and a vgabios just so
> coreboot can read the eeprom.

Ok lets say I can read the eeprom in vga option rom. I have 3 values
and can identify
what panel it is. fine.. and now? I need to know what
timings/resolution each supported
panel has.

switch (panel)
{
    case 1:
        set a hand full of variables
        break;
...
    case 7:
        set a hand full of variables
        break;
}

So I need to modify the VGA option sources everytime a new panel gets
added. And I am not
sure that you will accept patches that add vendor specific stuff if
there is a vendor independent
solution: EDID/EPI!

Is not an "interface" I want to build... I want to extend SeaVIDEOBIOS
to support EDID/EPI, which
_CAN_ be stored directly in the option rom - but its not a _MUST_.

I think I will finish my work and present a patch series for the
SesVIDEOBIOS part and we can discuss it
further. I hope that everybody sees/understands what I really want to
do - sometimes I really hate
discussing such stuff in a virtual world via mail and irc.