Arch Linux

jolivier

Member

Registered: 2012-05-30

Posts: 19

KMS using wrong video output

Hi all,

I have a Zenbook Prime and used it in dual screen mode via its HDMI output yesterday with xrandr. I unplugged the cable, conditnued using it, stopped it.
Now when I start it, as soon as initramfs finished loading, Linux uses the HDMI output to display my tty (even if no cable is plugged), so it prompts for my username on the HDMI output and the screen of my laptop becomes black. All the boot sequence up to this part is made on the correct screen but then this screen is not used anymore by linux. Even if with xrandr I try to use it I stays black. I can still control backlighting but nothing is displayed.

After some research, it appears that this decision is made by KMS (https://wiki.archlinux.org/index.php/Ke … de_Setting). When I disable KMS with nomodeset my tty is displayed on the laptop screen. The problem is that my graphic driver (intel) requires KMS to be enabled and thus prevents me from starting the X server without KMS.

So what I tried then is to force KMS to use my integrated screen instead of the HDMI output, with the video= parameters on the kernel command line. With these parameters I succeeded to disable the HDMI output, but could not enable mine with parameters like
video=HDMI-A-1:d video=eDP-1:1920x1080 D video=DP-1:1920x1080 D. So all my screens are black.

Also, if I plug a archiso usb key it starts its tty on the correct screen.

Any idea on how to debug better/fix this problem? I tried dmesg but see no interesting information about KMS...

Olivier

Last edited by jolivier (2013-07-31 12:55:08)

jolivier

Member

Registered: 2012-05-30

Posts: 19

Re: KMS using wrong video output

Ok I found this topic https://bbs.archlinux.org/viewtopic.php?id=167314, apparently my problem is related to theirs and is due to the 3.10 linux kernel. I thought this forum content was indexed by google but apparently not ^^, next time I'll also search here.