Kernel: 4.16.7
My monitor=E2=80=99s native mode is (some variant of) 5120x2880 at 60Hz. Wh=
en amdgpu is
loaded during startup, it picks up this mode from the monitor and switches =
to
it just fine.
However, when I start a minimal X (X.Org X server 1.19.5, amdgpu 1.3.0) wit=
hout
/etc/X11/xorg.conf and just an xterm and no window manager, I can see the f=
or a
fraction of a second the xterm window in the upper left corner of the screen
before the monitor turns black. It=E2=80=99s not turned off, the monitor=E2=
=80=99s power LED
shows that it=E2=80=99s on.
When I try to switch to another Linux console with Alt+Tab+F6, nothing happ=
ens;
the console is not switched (I can verify this because typing =E2=80=9Cecho=
-en '\a'=E2=80=9D
doesn=E2=80=99t beep).
After ca. 1:30 min the console finally *is* switched but remains black. The
kernel spews out messages about timeouts, and I have to reboot the machine
(from ssh or Ctrl+Alt+Del).
I can use X with 5K if I restrict the refresh rate to 30 Hz (from =E2=80=9C=
cvt 5120
2880 30=E2=80=9D).
This bug is present since kernel 4.15.10 or thereabouts, which was the first
version where amdgpu would work with dc =3D 1.