Created attachment 139031 [details] LightDM ant soccer Starting with Linux 4.16.2, when I logoff from KDE Plasma, I don’t get back into SDDM (just a black screen) or back into LightDM (wild random blocky screen, see attachment). I have a RX 580, DC is on. Same result on Linux 4.17rc2. Distro is Antergos/Arch. Monitor is connected via DP. Using SDDM, I can press ctrl + alt + F1 etc. to theoretically get to a tty prompt but the screen does stay black. But then, after pressing ctrl + alt + del numerous times, at least my system does a proper reboot. In LightDM, this does not work and I have to use the reset button. Worked with Linux 4.16.1 before.
Does https://patchwork.freedesktop.org/patch/217764/ help?
Applied the patch to Linux 4.17rc2, same problem.
Created attachment 139145 [details] Xorg.0.log after crash I have exactly the same blocky screen after logoff in SDDM with kernel 4.16.4 and RX 460. Xorg.0.log.amdgpu_logoff_crash contains xorg logs after crash. Distro is gentoo, I have 3 screens connected to RX 460 - all get blocky screen.
I have the exact same problem on Fedora 28 with kernels 4.16.4 and 4.17rc2 and amdgpu.dc=1 on who different systems, one with a RX 560 and one with a RX 580. Both use DP. >start computer, get lightdm, login to XFCE >logout >computer frozen My solution as of now is to use amdgpu.dc=0 which doesn't have this problem.
Created attachment 139195 [details] some kind of modern art by amdgpu.dc=1 upon logging out back into lightdm Tried again on the RX580 box with amdgpu.dc=1. Computer did NOT freeze but display did turn into some modern art project. ssh in shows this in the xorg log [ 748.979] (EE) modeset(0): failed to set mode: Invalid argument [ 749.548] (II) modeset(0): Disabling kernel dirty updates, not required. and nothing in dmesg. interestingly service lightdm restart did bring it back up normally. logging out again after that produced another pretty artistic ant-hive picture.
two more notes. a) my desktop with rx 470 and 3x4k monitors (HDMI/DP/DP) does not have this problem with amdgpu.dc=1 and kernel 4.16.4. b) my htpc with 2400g and rx 560 and one screen connected with DP totally has this problem with both 4.16.4 and 4.17rc2, logging out from xfce does not load lightdm correctly; instead screen turns into some sort of modern art. When this happens I can't switch to terminal with ctrl-alt-f2 BUT if I 1) turn the screen off 2) turn it on again then I can get to a terminal by ctrl-alt-f2 and go back to lightdm with ctrl-alt-f1 and it shows correctly and normally instead of modern art. c) I tried attaching another monitor to the rx 560 and both monitors turned into modern art upon logout. I just tried this to see if number of monitors matters. There's some reason one box with rx470 works fine and two with rx560 and rx580 have this problem.
I don't seem to have this problem with git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git from 20 minutes ago. Booted with that git and no problem logging in and out again. Rebooted with 4.17rc2, problem. Rebooted again with git, no problem. I'm guessing it's this that fixed it, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0f940fac655d5a728bc5ef6204d2ec4c3b3ea6c3
I can confirm, works again on Linux 4.17 RC3. But label this bug RESOLVED WORKSFORME is the wrong attitude. It needs to get fixed in 4.16 too.
BTW, 4.17 RC3 does not bring back my DP monitor after I have turned it off, so this situation is by far not hunky-dory.
A fix should land in 4.16 stable soon: https://www.spinics.net/lists/stable-commits/msg86375.html
Linux 4.16.7 fixed issue for me.
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