Thanks for the animation. I think that flicker is occurring in the LCD itself. The reason is that the old gradient (which was only used in Ubuntu 18.10) covers more colours than 24-bit RGB can support. On top of that, if your monitor is only 18-bit RGB in hardware then you will see even fewer colours and the display/kernel will flicker on purpose to create the illusion of all the shades it can't really display. This is called temporal dithering, or Frame Rate Control:
https://en.wikipedia.org/wiki/Frame_rate_control Essentially that gradient is just a pathological case which will make the shimmering/flickering more visible than it usually is. For this and other reasons, I reported a bug 1789355 too. In the end this is a hardware limitation. But it is a common one which the kernel driver should have some control over. You should be able to configure the nouveau kernel driver directly using something like: xrandr --output DVI-I-1 --set "dithering mode" "off" or xrandr --output DVI-I-1 --set "dithering mode" "static 2x2" based on your Xrandr.txt which says: dithering depth: auto supported: auto, 6 bpc, 8 bpc dithering mode: auto supported: auto, off, static 2x2, dynamic 2x2 I am going to reassign this bug to the kernel because it sounds like the only software solution possible here would be for the kernel to automatically choose a less annoying dithering mode for this model of monitor. P.S. The gradient is completely gone in Ubuntu 19.04 so you won't have any trouble there. ** Package changed: xorg-server (Ubuntu) => linux (Ubuntu) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1819023 Title: [nouveau] Scrolling screen flicker, especially on default Ubuntu lock screen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1819023/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
