https://bugs.freedesktop.org/show_bug.cgi?id=105971

Bug ID: 105971 Summary: DVI port is not detecting connected monitor with 4.16.0+ kernel and amdgpu.dc=1 set Product: DRI Version: unspecified Hardware: x86-64 (AMD64) OS: Linux (All) Status: NEW Severity: normal Priority: medium Component: DRM/AMDgpu Assignee: dri-devel@lists.freedesktop.org Reporter: sass.joel@gmail.com

Created attachment 138731 --> https://bugs.freedesktop.org/attachment.cgi?id=138731&action=edit dmesg output from amdgpu.dc=0 switch

Hello. I'm trying to get 4 monitors working on the same desktop. Video card is a Radeon RX560.

root@nope:/tmp# lsb_release -a LSB Version: core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch Distributor ID: Ubuntu Description: Ubuntu 16.04.4 LTS Release: 16.04 Codename: xenial

root@nope:/tmp# uname -a Linux nope 4.16.0+ #1 SMP Mon Apr 2 15:52:14 CEST 2018 x86_64 x86_64 x86_64 GNU/Linux

With kernel switch amdgpu.dc=1, DVI port doesn't detected connected monitor, but displayport MST is detected and utilized properly, allowing me to output video to three monitors from a single displayport.

With kernel switch amdgpu.dc=0, DVI port properly detects connected monitor, but displayport MST is not detected. Instead, displayport MST acts as a single output, and video output is mirrored to all three connected monitors.

This appears to be a kernel issue. Kernel was retrieved from git repo github.com/M-Bab/linux-kernel-amdgpu-binaries

I'm running the AMDGPU.UBUNTU kernel on that repo.

I'll attach dmesg, xrandr and Xorg.0.log output from both kernel switches.

I'm running amdgpu.dc_log=1 kernel switch for verbose logging.