Arch Linux

Mahboi

Member

Registered: 2022-11-02

Posts: 4

Second Screen failure on startup [HW problem, SOLVED]

Hello,

Since coming to kernel 6.0 (currently 6.0.6.arch1-1), my second monitor gives some serious startup troubles.
It constantly starts and stops until eventually properly starting after an x amount of retries. This is very recent and coincides with the update to 6.0 around last week.
It does this regardless of using KDE plasma with Wayland or Xfce with X.
On Plasma, I could see the monitor coming on and the sound being set to that monitor, then immediately turn off. If I opened Plasma or Xfce's Display module, it just said "disconnected" or went back to 1 monitor. It keeps doing that for minutes.
This is very annoying and seems to happen on every coming out of suspend, hibernate, or sometimes even cold restart.

I run an AMD GPU (RDNA 2) with Mesa's latest version (22.2.1-1).
I suspect that it's the latest batch of AMD pushes to the kernel for the upcoming RDNA 3 that might have screwed something wrong, but how do I debug this?

Please advise.

Last edited by Mahboi (2022-11-22 14:53:13)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,261

Re: Second Screen failure on startup [HW problem, SOLVED]

You can in general avoid a lot of potential gotchas here by enabling early KMS: https://wiki.archlinux.org/title/Kernel … _KMS_start

FWIW you might have to get more specific as I can't reproduce any of his on a 6900XT. Generally check/look at/post xorg and journal logs like e.g. presented by

sudo journalctl -b

  https://wiki.archlinux.org/title/List_o … n_services .

Also HDMI cables are very finicky and can break easily, to be absolutely certain it's a kernel regression see whether you can really not reproduce on older kernels/maybe test LTS or so.

Mahboi

Member

Registered: 2022-11-02

Posts: 4

Re: Second Screen failure on startup [HW problem, SOLVED]

You can in general avoid a lot of potential gotchas here by enabling early KMS: https://wiki.archlinux.org/title/Kernel … _KMS_start

FWIW you might have to get more specific as I can't reproduce any of his on a 6900XT. Generally check/look at/post xorg and journal logs like e.g. presented by

sudo journalctl -b

  https://wiki.archlinux.org/title/List_o … n_services .

Also HDMI cables are very finicky and can break easily, to be absolutely certain it's a kernel regression see whether you can really not reproduce on older kernels/maybe test LTS or so.

I'll try early KMS first, but I don't understand the wiki:
"For in-tree modules, add kms to the HOOKS array in /etc/mkinitcpio.conf.

For out-of-tree modules, place the module names in the MODULES array. For example, to enable early KMS for the NVIDIA graphics driver:"
I have no clue what is an "in-tree" or an "out-of-tree".

Will:

MODULES=(amdgpu)
HOOKS=(base udev autodetect modconf block filesystems keyboard resume fsck kms)

do?

d.ALT

Member

Registered: 2019-05-10

Posts: 959

Re: Second Screen failure on startup [HW problem, SOLVED]

Will:

MODULES=(amdgpu)
HOOKS=(base udev autodetect modconf block filesystems keyboard resume fsck kms)

do?

Yup! Remember to rebuild your InitRamFS before rebooting:

# mkinitcpio -P

---

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<50,17,III,I>    misericordia e giustizia li sdegna:
<51,17,III,I>    non ragioniam di lor, ma guarda e passa.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,261

Re: Second Screen failure on startup [HW problem, SOLVED]

Since the mkinitcpio 32 released recently you can either add the MODULES= as one used to or just set the kms hook in the hooks line which will automatically pick the correct modules as they exist on your system, both will logically result in the same end goal, so it shouldn't inherently matter much.

Mahboi

Member

Registered: 2022-11-02

Posts: 4

Re: Second Screen failure on startup [HW problem, SOLVED]

Early KMS seems to have solved the problem! Thank you both very much.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,261

Re: Second Screen failure on startup [HW problem, SOLVED]

Great! Please mark as [SOLVED] by editing the title in your first post.

Mahboi

Member

Registered: 2022-11-02

Posts: 4

Re: Second Screen failure on startup [HW problem, SOLVED]

Ok so for the little story, KMS didn't fix anything, just made it work fine once, then the problem came back.
Then the second screen went from taking 5-10s to taking 30s, to taking whole minutes, to taking over 10 mins, and flickering when it finally started.
And I remembered your HDMI cable idea, changed it, didn't fix anything. I then asked a friend to lend me one of his monitors, it worked instantly.

The monitor was pretty old and was simply dying from a tired PSU, it just happened to start its failed boots right after I upgraded to 6.0.
Just wanted to say thanks for your help with the "it may be hardware" idea. Time to buy a new monitor, solo monitor after years of dual mono is hell.