[coreboot] [Broadwell-U]How the eDP, DDI1, DDI2 are enabled?

[Zheng Bao]

In text mode,
only one display can be enabled.


Can this enabled display port be DDI1 or DDI2?

I just extracted VBIOS from BIOS provided on board. I assume the display ports are enabled based on the board settings.

Can I just set register "gpu_panel_port_select" = "2" to enable DDI1?


Thanks.


Zheng


________________________________
From: Nico Huber <nico.h at gmx.de>
Sent: Monday, August 7, 2017 9:32 AM
To: Zheng Bao; coreboot at coreboot.org
Subject: Re: [coreboot] [Broadwell-U]How the eDP, DDI1, DDI2 are enabled?

On 06.08.2017 05:18, Zheng Bao wrote:
> At which stage do you want to enables these ports? in the OS? or during
> boot? if the latter, which payload do you use?
>
>
> Zheng: I want to enable these display port during boot. The payload is SeaBIOS.

You have to set your VGA BIOS to a VESA mode AFAIK. In text mode,
only one display can be enabled. Though, I don't know how to do that
with SeaBIOS. There might be a compile time option?

There are also many options inside Intel's VGA BIOS in a structure
called Video BIOS Table (VBT). IIRC, you can set it to start in VESA
mode with multiple displays there.

There's also an open-source solution for Intel gfx bringup, libgfxinit.
Alas, it's not ready to use on Broadwell (it works generally just some
steps are missing to make it work with coreboot).

Nico

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