For more than a month I'm having a crash problem with the kernel 5.11. It boots up, but when loadaded the display manager (tried SDDM and GDM), the system freezes. It occurs in a Dell Inspiron laptop with AMD GPU Radeon R7.
Well, I finally found a solution in the Bugzilla of kernel [https://bugzilla.kernel.org/show_bug.cgi?id=212133]. The solution is add the 'modprobe.blacklist=amdgpu 3' parameter to the GRUB kernel line. It works! The only problem is having to start the graphical server manually. I opened this thread to make developers aware of the problem, if they are not already. I am hopeful for a better and definitive solution soon.
