[coreboot] [skylake] Can not turn monitor on

Nico Huber nico.h at gmx.de
Fri Oct 5 22:27:01 CEST 2018

On 10/5/18 4:43 PM, Zheng Bao wrote:
> I transfer all the GPIO setting to my code.

What do you mean? did you have wrong GPIO settings before?

> After this, the linux can turn the monitor on, but in BIOS stage,
> monitor can not be turn on.
> Is that the way it is? Can BIOS turn the display on?

What exactly do you mean with BIOS? a VGA BIOS? it should work with the
correct VBT. Same with a GOP driver. I'll add Matt in CC who has more
experience with the proprietary graphics solutions.

Personally, I would just implement the backlight control in coreboot
and use libgfxinit as open-source solution. Register documentation can
be found here [1][2] and soc/intel/broadwell/igd.c:311..344 as example
how it worked on older platforms. Everything else you need are the
correct settings for your board/panel which you can find by decoding
the VBT or just dump the registers when Linux initialized it.




[2] PP_* and SBLC_PWM_CTL[12] in


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