On Kubuntu, resuming the laptop from sleep leaves me with a blank screen and the mouse only. The mouse moves normally which indicates that the touchpad is working. It once showed errors that the EXT4 partition is read only or something like that but I couldn't get it to show again. I suspect that the SSD is not resuming from sleep.
Laptop specs: Ryzen 5500U + Radeon GPU, 8GB RAM, Kioxia SSD. Software: Kubuntu 21.10, Plasma 5.22.4, Linux kernel 5.13
I booted the laptop from a live USB and suspended it then resumed. The laptop resumed properly but the SSD didn't show up, so referring to the logs I found:
nvme nvme0: Device not ready; aborting reset, CSTS=0x3
nvme nvme0: Removing after probe failure status: -19
Which turned out to be a known issue with some NVMe drives having broken sleep support. The solution (Quoting from arch wiki):
As a workaround, add the kernel parameter
iommu=softto use a software replacement for the hardware IOMMU. (For further details, see this documentation.) This has the potential to cause some slight processing overhead.
Edit: For those who don't know how to add a kernel boot parameter, refer here. The short version of it is:
1- Type sudo nano /etc/default/grub in your terminal
2- Find the line with GRUB_CMDLINE_LINUX_DEFAULT
3- Add the parameter, it should look something like this (may slightly differ if you have other kernel options):
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash iommu=soft"
4- Save the file by pressing ctrl+X then y+enter
5- type sudo update-grub
6- Reboot and you should be done.
Edit: Since at least kernel 5.19, this workaround is no longer working, the one that works is iommu=off.