ThinkPad T480 screen flickering on Ubuntu 24.04 still?

Question

so I've read:

Screen flicker after fresh install of Ubuntu 22.04

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1958191

Could it really be that screen flicker still has not been fixed since 2022 or 22.04 version of Ubuntu?

Or is my hardware just bad, I got a T480 ThinkPad with a 8th Intel. Graphic Unit is 620. I understand the fix in the link above, but have some questions:

1. Is this fix on costs of more power drain?
2. What is intel_idle.max_cstate=2?
3. Why is this issue still in 2024 Ubuntu? Is it really just bad hardware? What is going on? I have no problems with it on Win11.

I hope some of you can help me understand all of that!

Answer 1

I had the same issue. I have only tried Ubuntu 24.04.1.

After a flickering episode I found this in the dmesg log sudo dmesg

[59913.579290] i915 0000:00:02.0: [drm] ERROR CPU pipe A FIFO underrun

I changed /etc/default/grub adding these two settings and the issue was resolved. I forget where I found them, and I'm not sure what they do, but see https://wiki.archlinux.org/title/Intel_graphics .

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.enable_dc=0 intel_idle.max_cstate=2"

Then I ran sudo update-grub and rebooted and verified the new kernel options were effective:

$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-6.8.0-51-generic root=UUID=aff5bdac-a2ed-4e0f-8c02-d574fddc6bdc ro quiet splash i915.enable_dc=0 intel_idle.max_cstate=2

I haven't had any more i915 FIFO underrun messages since then.