"CPU1 stuck for XXs: Xorg" since update to linux-4.16.x

Submitted by Clemens Eisserer

Assigned to Default DRI bug account

Link to original bug (#106474)

Description

Created attachment 139489
screenshot

After updating the Laptop of a friend running Fedora 27 to linux-4.16.4/5/6 it frequently gets stuck when starting Xorg - please see the attached screenshot.

The machine is a AMD Beema based Hewlett-Packard HP 355 G2/22C1, BIOS F.10 02/12/2015 running the latest Fedora 27 packages.
Graphics stack is default (glamor, radeon kernel module).

Linux-4.15.17 works absolutly flawless.

Attachment 139489, "screenshot":