Can't send video signal to portable monitor (USB-C, DP Alt Mode) when it also needs power supply
Brief summary of the problem:
Portable monitors can't be connected and used when they need both power and video signal: it is only powered, but no video signal is being sent. The portable monitor (here, an Arzopa Z1C needing 12W), needs to be powered through an external power supply (e.g. power bank) prior to a connection to the computer (Framework Laptop 16) for the video signal to be correctly transmitted.
The problem occurs on all Linux distributions, including NixOS Unstable, Ubuntu 24.04, and Fedora 40.
DP Alt Mode is supported on the computer, I tried on all ports, with multiple cables including the stock one. The monitor is working correctly on computers with NVidia GPUs or Intel graphic chipsets.
List of user-reported issues:
- https://community.frame.work/t/external-monitors-hdmi-and-dp-alt-mode-not-working-on-linux/52849/18
- https://www.reddit.com/r/techsupport/comments/18mr0y8/portable_monitors_and_dp_alt_mode_14_issues/
- https://www.reddit.com/r/framework/comments/1bpc103/fw13_external_monitor_via_usbc/?share_id=r5olyuq2KSj3c9HuwTV6u
- https://community.frame.work/t/displayport-over-usb-c-not-working-amd-13/41583
Nota bene: 3 out 4 reports above concerns framework computers (both 13 and 16), but not all, and the framework technical support already told me the issue wasn't on their side.
Maybe related to this issue? #2924
Hardware description:
- CPU: AMD Ryzen 9 7940HS w/ Radeon 780M Graphics
- GPU: 03:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Navi 33 [Radeon RX 7700S/7600/7600S/7600M XT/PRO W7600] [1002:7480] (rev c1)
- System Memory: Memory: total: 60 GiB available: 58.67 GiB used: 6.11 GiB (10.4%)
- Display(s): Portable monitor Arzopa Z1C
- Type of Display Connection: USB-C (DP Alt Mode)
System information:
- Distro name and Version: nixos arch: x86_64 bits: 64 compiler: gcc v: 13.3.0
- Kernel version: 6.9.7
- Custom kernel: 6.9.7-zen1
- AMD official driver version: N/A
How to reproduce the issue:
To reproduce the issue:
- Boot a stock live usb of Fedora 40,
- Plug the portable external monitor -> powered on but no video signal,
Complete logs showing an amdgpu crash are here: https://gist.github.com/clementpoiret/ed7263d1dcbbfebc962bb36d745ec55d