DisplayPort MST - Only one of two screens working (but both detected)
Brief summary of the problem:
I'm currently trying to use my two display monitors connected via DisplayPort using MST. Both screens show up in the KDE Settings but the second in line (aka connected to the first monitor) is marked as disabled and whenever I try to enable it it switches back to being disabled.
Note: I was forwarded to this nice place from the kde bugtracker
Hardware description:
- CPU:
AMD Ryzen 9 6900HS with Radeon Graphics
- GPU:
03:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Navi 23 [Radeon RX 6650 XT / 6700S / 6800S] [1002:73ef] (rev c0)
07:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Rembrandt [Radeon 680M] [1002:1681] (rev c7)
- System Memory: 38gib
- Display(s):
2x Benq PD2700U
- Type of Display Connection:
DP DaisyChain
System information:
- Distro name and Version: Manjaro (latest on branch testing)
- Kernel version:
6.8.7-1-MANJARO
- DE: Plasma 6.0.4
How to reproduce the issue:
- Connect two DP Monitors via DisplayPort MST (last one in the chain stays black)
- Try to enable via system settings
- On apply the system disables the monitor again
Happens both with Wayland and X11
Happens both via the System Settings UI and the kscreen-doctor utility (kscreen-doctor output.DP-12.enable
)
Attached files:
I've followed this guide to create the following log drm-debug.log
Started logging before trying to enable the monitor and stopped after trying it.
I assume that the error happens at the following timestamp but since I'm not really sure what the real error is this is just my best guess:
[ 1624.137475] amdgpu 0000:07:00.0: [drm:drm_dp_mst_atomic_check_payload_alloc_limits [drm_display_helper]] [MST PORT:000000002de10ff2] not enough time slots in mst state 00000000d608446a (avail=3)