Ubuntu – Color distortion after coming out from suspend on Ubuntu 18.04

This is happening because the radeon module is taking control of the device before pci-stub, so you need to reverse the load order.

Blacklist the radeon module:

$ echo blacklist radeon | sudo tee -a /etc/modprobe.d/blacklist.conf

And add the module to initramfs:

$ echo radeon | sudo tee -a /etc/initramfs-tools/modules
$ sudo update-initramfs -u

After, reboot. Problem solved!

I finally managed to fix it, and here are the steps for people having the same issue.

1. Switch from gdm3 to lightdm

To do this, open a terminal and type sudo apt-get install lightdm, or sudo dpkg-reconfigure lightdm and when asked, select lightdm as your default display manager

2. Try the fix

1. Start your system and wait for the GRUB menu to show (if you don't see a GRUB menu, press and hold the left Shift key right after starting the system).

2. Now highlight the kernel you want to use, and press the e key. You should be able to see and edit the commands associated with the highlighted kernel.

3. Go down to the line starting with linux and add at the end: amd_iommu=off. Generally, the end of the line will look like this: quiet splash amd_iommu=off

4. Now press Ctrl + x to boot.

5. Open your session and try suspending by closing the lid

3. Make the fix permanent

1. From a terminal (or after pressing Alt + F2) run:

   gksudo gedit /etc/default/grub

   (or use sudo nano if gksudo or gedit are not available) and enter your password.

2. Find the line starting with GRUB_CMDLINE_LINUX_DEFAULT and append amd_iommu=off to its end. For example:

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash amd_iommu=off"

   Save the file and close the editor.

3. Finally, start a terminal and run:

   sudo update-grub

   to update GRUB's configuration file (you probably need to enter your password).

I also noticed that you cannot suspend with a long press on the power button in the top-right Ubuntu menu, as it results to a crash on wake up.

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Sources:

https://bbs.archlinux.org/viewtopic.php?pid=1858315#p1858315

https://askubuntu.com/a/19487/981926

https://askubuntu.com/a/152381/981926