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@gmx.de Sent: Monday, August 7, 2017 9:32 AM To: Zheng Bao; coreboot@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