Public bug reported: Upgrading from 18.04 to 18.04.3 on a Mac Pro 5,1, the Polaris 11 AMD card, RX 460 began being very slow to display gdm3; screens would come on black then go back to sleep in a cycle. Logging into Gnome takes anywhere between 60 and 90 seconds. If the screen is allowed to go black from inactivity, it takes a long time to return to usability.
>From experimenting, setting dpm=0 in the grub boot options makes this particular problem go away at the cost of extremely poor 3D performance. 3D performance was already much weaker than it should have be. I have tried the newest mainline kernel and it there is no difference. I also have an AMD Firepro W5100 which is a Polaris 10 card. It operates perfectly. Even before this particular problem, the W5100 out performed the RX 460 which should not be the case. The RX 460 was tested in a spare Windows 10 computer and works fine. It was also tested in each of the PCIex16 slots of the Mac Pro 5,1. ** Affects: ubuntu Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1840514 Title: amdgpu on RX 460 in 18.04.3 does not change state To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1840514/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs