Arch Linux

gaston

Member

Registered: 2021-01-02

Posts: 2

[SOLVED] Screen display problems since kernel 5.9

Hi, screen is not displaying properly since Linux 5.9. But it is not X; even the virtual terminal (ALT+F1) looks odd.

Latest kernel to date (5.10.3.arch1-1) has the problem.
Linux 5.8.* worked fine.
Now I am using 5.4.86-1-lts to work around the issue.

I have compared the outputs of

• sysctl -a

• dmesg

• xrandr

but have not found any difference that looks like the cause of the problem.

I am running on a Thinkpad E490 with Intel drivers.

Compare the colours:
Here is a screen shot with kernel 5.10.3 (bad): https://ibb.co/TR4pZVM
Here is the same screen shot with kernel 5.4.86 (good): https://ibb.co/GMHP7pd

Any suggestions on what I should look for?

UPDATE: I realized "bad" kernels are choosing a refresh rate of 141Mhz. If I force it to use ~60Mhz the problem goes away. I did it using the following command:

xrandr --output eDP1 --mode 1920x1080 --rate 59.93

So, I am trying to figure out how to make this refresh rate persistent. Any suggestions are very appreciated.

Last edited by gaston (2021-01-06 13:34:16)

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 74,307

Re: [SOLVED] Screen display problems since kernel 5.9

Sounds more like an issue of https://wiki.archlinux.org/index.php/Va … fresh_rate ?
(The "bad" randr output say 60.01, not 141)

And least the modesetting driver supports the config and it seems the i915 kernel module now is -somewhat- capable of it…
https://gitlab.freedesktop.org/xorg/xse … quests/457

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gaston

Member

Registered: 2021-01-02

Posts: 2

Re: [SOLVED] Screen display problems since kernel 5.9

Thanks, seth. I could not confirm this is a variable refresh rate issue. I am using Intel drivers and the information about VRR for them is little.

However I was able to "fix" it by adding the call to xrandr I wrote above in the Xsetup script of xdm. I am sure this is not the best solution, or even correct, but it works.