Install kernel mainline

 

• In Terminal, enter uname -mrs to determine the current kernel version.
• Check and get any needed updates by entering sudo apt update && sudo apt upgrade.
• Add the ppa for the kernels: sudo add-apt-repository ppa:cappelikan/ppa -y
• Again, get the update list, now that the new repository has been added: sudo apt update
• Install the latest mainline kernel: sudo apt install mainline -y
• Reboot.

Dell 9310 fix suspend issue

 

BIOS, turn off Early Logo Display to OFF in the Sign of Life options

BIOS, disable Secure Boot

In the system, edit and configure in /etc/default/grub to add to the kernel options : mem_sleep_default=deep

My current kernel options are : GRUB_CMDLINE_LINUX_DEFAULT="quiet splash mitigations=off mem_sleep_default=deep"

(do NOT use mitigations=off unless you seriously know what you're doing)

Reboot. TO check if the deep sleep is on :

cat /sys/power/mem_sleep

Should return :

s2idle [deep]

The deep here confirms the deep sleep mode is turned on.