Description of problem:

After installing upgrades on my fedora 24 test system on Friday, I tried booting it today. The machine came up through the normal boot logo. Then instead of a login screen, I got a text-mode message:

[drm:si_dpm_set_power_state [radeon]] *ERROR* si_restrict_performance_levels_before_switch failed

ctrl-shift-F2 switches to a text-mode login screen, and the machine is up and listening on ssh. Just no...workstation part.

Version-Release number of selected component (if applicable):

Fedora (4.5.2-301.fc24.x86_64) 24 (Workstation Edition)

How reproducible:

Still occurs with the previous kernel 100% so far.

Steps to Reproduce:
1. dnf system-upgrade to 24 on a crufty system
2. dnf upgrade daily for a week.
3. restart

Actual results:

No graphical login.

Expected results:

Normal login screen.

Additional info:

Switching back to tty shows a more complete boot log. All steps are green (OK) except for:

Starting Cleanup udevd DB...
Starting Plymouth switch root service...
Starting Switch Root...

Let me know if you need anything else. I'm familiar with the command line, but not with X or systemd debugging.