HP Pavillion 15 Freeze Fix

My new Laptop would randomly freeze particularly when left idle with nothing obvious appearing in the logs.

The cause was finally traced to two issues both fixed by adding kernel options. This was done by editing the following line in /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="i915.enable_psr=0 nomodeset"

and then running

~$ sudo update-grub2

The first option

i915.enable_psr=0

turns off the Panel Self Refresh (PSR) which is a power saving feature for the Intel iGPUs.

The second option

nomodeset

turns off the screen resolution being set by the kernel. This is apparently so that you can display a high resolution splash screen on boot

So both issues appear to be screen related and the real question is why are they in the Ubuntu 18.04 LTS kernel in the first place. At best they should be modules rather than hard baked in the kernel itself but really they should be things you add if you wish after install. This is particularly true for the PSR. The laptop has a Nvidia GPU. We are going the way of Windows :-(