After doing a bit of research and refusing to recompile the graphics stack manually I found you need to do 2 things to almost completely resolve this issue: set a cstate restriction parameter for the kernel in /etc/default/grub and update the AMD graphics driver.
Open Terminal and open the file for editing with root privileges, for example (if you don't have mousepad you could use nano)
sudo mousepad /etc/default/grub
Change the line beginning GRUB_CMDLINE_LINUX_DEFAULT= so that after your edit it includes the parameter intel_idle.max_cstate=1, for example mine says:
GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1 intel_idle.max_cstate=1"
You can keep other parameters, such as quiet and splash which may be there already.
save and exit the text editor, and run this command to update the GRUB configuration:
sudo update-grub
Now add a PPA for AMD graphics drivers:
sudo add-apt-repository ppa:oibaf/graphics-drivers
sudo apt update && sudo apt upgrade
Now reboot.
This solution should work for other flavors of Linux (ie mint, mx, manjaro etc...) and other AMD powered machines experiencing this issue.
Do not use screen lock or system suspend and you will most likely never have a freeze again!
When I choose to stop being lazy and resolve system lock freeze issues I will update this response.
AMD has not released any official proprietary drivers for Ubuntu 20.04 as of this posting, when and if they do, I would recommend trying them.
So, eventually I managed to get the touchpad working on Ubuntu 18.04, kernel version: 5.3.0-46-generic thanks to comments on this link:
https://www.reddit.com/r/linuxquestions/comments/f9h0q4/touchpad_issue_lenovo_s14515iil/
Basically what needs to be done is:
Open the file /etc/default/grub for editing, for example by running
sudoedit /etc/default/grub
Add to the line beginning GRUB_CMDLINE_LINUX_DEFAULT: "i8042.nopnp=1 pci=nocrs" so that it reads:
GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp=1 pci=nocrs"
If other parameters are there between the double quotes, it may be OK to leave them.
Save the file and exit
Run this command to update the GRUB configuration:
sudo update-grub
Reboot
Best Answer
As of early August 2018, I was able to get my cursor working (ELAN 061C)--without patching or compiling the kernel from source--by just upgrading to the 4.18-rc7 mainline build.
Instructions can be found here at TecMint.