The temporary answer that I found to the problem (a known issue to the model), is to start elementary in advanced options, and go into recovery mode. Due to the fact this 2011 MBP model features 2 video adapters (thus now on the Intel one), the settings work just fine, however there's no way to either resume from suspend or hibernate on this mode, neither on Ubuntu 19.04 that I installed as well (it was also an easy answer to install grub2, reinstall ReFind and have access to the advanced boot options), just to test the distro. Whatever I tried, I could not resume from suspend or hibernate.
However, apart from that, the system is working just fine.
Though there's a more elegant answer, than the before temporary one that works, only if you have access to grub menus.
Here's the walkthrough: (as of Opiniated Logic, a more elegant answer):
Disable the AMD graphics card permanently:
Once you reboot you’ll need to press e in the grub menu line you are expected to boot from.
Look for the line:
Once you’ve found it, type the following lines underneath to disable the AMD graphics card:
outb 0x728 1
outb 0x710 2
outb 0x740 2
outb 0x750 0
Next find the kernel line and after “quiet splash” , add the following:
i915.lvds_channel_mode=2 i915.modeset=1 i915.lvds_use_ssc=0
After checking to make sure that we’re mistake-free press F10 (likely Fn + F10) on the Macbook. This should allow us to boot with the integrated Intel graphics card.
This will load your new Ubuntu Linux system with Intel graphics.
Now once booted successfully into the system with working graphics, we just need to set things up so you don’t need to do that "ever" again. Start a Terminal and run the following command to edit the necessary file:
sudo gedit /etc/default/grub
This will ask you for your user account password to get admin privileges. Enter it and when the file opens search for the line:
and change it to:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.lvds_channel_mode=2 i915.modeset=1 i915.lvds_use_ssc=0"
Once this change is made, check for errors then save and exit.
Next we’ll run another command in the Terminal:
sudo gedit /etc/grub.d/10_linux
Again, enter your password if asked and when the file opens find the line
echo " insmod gzio" | sed "s/^/$submenu_indentation/"
And place the following immediately before this line:
echo " outb 0x728 1" | sed "s/^/$submenu_indentation/"
echo " outb 0x710 2" | sed "s/^/$submenu_indentation/"
echo " outb 0x740 2" | sed "s/^/$submenu_indentation/"
echo " outb 0x750 0" | sed "s/^/$submenu_indentation/"
Check to make sure that everything is correct and save, then exit gedit once more.
This will update the boot loader settings we just changed and make them stick. The next time we reboot we won’t have to type out all those obnoxious commands to disable and enable things.
Personal note: you will have to keep this info handy in case there's a kernel or system update that erases your updated grub's config: in that case, you will have to update grub again making sure the two files are updated again and grub updated consequently.