[SOLVED] Cannot have DP+HDMI at the same time

0BADC0DE · 2023-11-12 19:00:39

SOLVED! Read below!

Laptop: TUXEDO InfinityBook S 14 Gen6/L14xMU, BIOS 1.07.12NRTR1 05/01/2021
Connected to: Lenovo ThinkPad Dock Gen2 40AS via its USB-3/Thundebolt 3 port Docs here
On display port: Samsung LU28R55 (3840x2160)
On HDMI port: Samsung S24D300 (1920x1080)

Software system:

Kernel Version : 6.6.1.zen1-1
Plasma Version : 5.27.9-1
KDE Version : 23.08.3-1
Frameworks Version : 5.111.0-1
Qt5 Version : 5.15.11+kde+r12-1
Qt6 Version : 6.6.0-3
Wayland Version : 1.22.0-1
XOrg/Wayland Version : 23.2.2-1
Mesa Version : 1:23.2.1-2
LibVA Version : 2.20.0-1
VDPAU Version : 1.5-2

lspci output
lsusb output
xrandr output

Laptop USB-C is actually a Thunderbolt4/USB-4 port.
My laptop lid would/should normally be closed while both external displays are enabled in the settings which can correctly list all threee displays each with its own resolution: 1 builtin and 2 external.
The "(i) Identify button" just displays a message on the DP display.
Th HDMI display doesn't dislay the identification string as well as anything at all: it just stays black.
If I disconnect the DP cable I need to open the laptop lid to activate the HDMI display. Then I can close it again.
If I reconnect the DP cable, the DP display stays black no matter what I do with system settings.
I need to disconnect HDMI cable and open/close the lid to get the DP display working.

I am not sure whether this setup can acytually work or not.
Any idea?

I suspect USB3 bandwidth coul not be enough...

Last edited by 0BADC0DE (2023-11-12 19:11:31)

0BADC0DE · 2023-11-12 19:12:30

I had to comply (OF COURSE) with refresh rate constraints!
I put DP display to 30 Hz and the HDMI one to 50 Hz (cannot bring it to 30 Hz).
And it worked!

Arch Linux

#1 2023-11-12 19:00:39

[SOLVED] Cannot have DP+HDMI at the same time

#2 2023-11-12 19:12:30

Re: [SOLVED] Cannot have DP+HDMI at the same time

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