Comment 10 for bug 1866984

For the following error in the initial post:

[ 421.603306] [drm] Reducing the compressed framebuffer size. This may lead to less power savings than a non-reduced-size. Try to increase stolen memory size if available in BIOS.

This can be solved by disabling framebuffer compression, which will have a pretty negligible impact on power management. @mvanross, I'm also working on a T480, so this may help you.

To disable, edit /etc/default/grub (you need superuser privilege to do this)

change:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.i915_enable_fbc=0"

and run:

sudo update-grub