https://bugs.kde.org/show_bug.cgi?id=475168
Bug ID: 475168
Summary: External monitor not detected on Advanced Optimus
Classification: Plasma
Product: kwin
Version: 5.27.8
Platform: Archlinux
OS: Linux
Status: REPORTED
Severity: critical
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: evors...@protonmail.com
Target Milestone: ---
SUMMARY
***
When plugging in a monitor into the HDMI port on the laptop, the monitor is not
detected in Display Settings panel.
The laptop that has the issue is a Sager NP8775E, (Identical to Tuxedo Gemini
Gen 2, and Clevo PD70SNE-G) but I believe you will be able to reproduce this
issue on any laptop that has nVidia's Advanced Optimus controlling the handoff
between the integrated and dedicated GPU's where the dGPU is hard-wired to the
HDMI port.
The laptop has no xorg.conf, and relies completely on auto detection for the
xserver setup.
On X11, this works well, and the issue mentioned below is not present. On
Wayland, it also works really well, apart from the issue below.
***
STEPS TO REPRODUCE
1. Run a Wayland KDE session on a notebook that has nVidia's Advanced Optimus,
and where the dGPU is hard-wired to the HDMI port.
2. Plug a monitor into the HDMI port on the laptop
OBSERVED RESULT
Monitor is not detected. As far as I can tell, there is no event. The dedicated
GPU does not wake up, and there is no output to the monitor.
EXPECTED RESULT
The monitor to be detected, configured and presented in the Display Settings
panel.
SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.27.8
KDE Frameworks Version: 5.110.0
Qt Version: 5.15.10
Kernel Version: 6.5.5-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 32 × 13th Gen Intel® Core™ i9-13900HX
Memory: 62.5 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: Sager
Product Name: PD5x_7xSNC_SND_SNE
System Version: Not Applicable
ADDITIONAL INFORMATION
Ah it took me embarrasingly long to get here.
First I thought it was an issue with the nVidia drivers, then with Wayland
itself. Through all this I did manage to get a lot of information that could
help.
First, a quick description. nVidia's Advanced Optimus is a newer way of
managing the two video cards in some laptops. The laptop panel is driven
through a MUX that the drivers control, and it decides whether to take input
from the integrated or dedicated CPU. This part works flawlessly under Windows,
X11 and Wayland.
The HDMI port on these laptops is hardwired to the dedicated high power GPU.
Under X11, when I plug a monitor into the HDMI port, it is detected, configured
and presented to me in the display settings panel. In Windows, it also just
works.
When the external monitor is plugged into a usb-c laptop dock, it also works on
Wayland.
Interestingly enough, I can switch the laptop to dedicated GPU only mode in the
BIOS, and then I am able to get output to the monitor connected to the HDMI
port, but it is not detected as a separate monitor, and so is just a duplicate
of the laptop panel.
I am fully aware that this hardware is rare and quite expensive, and that not
many people have access to it.
I am willing to run tests and provide logs to you if you feel like tackling
this issue. I can also compile and run development packages from git if you
think you have a fix we can try.
I use Wayland as my daily driver, and it was more than a month before I even
thought of trying this on X11, which is a testament to how well this compositor
works on Wayland.
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