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

0BADC0DE
Member
From: Regnum Utriusque Siciliae
Registered: 2018-02-21
Posts: 312

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

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)


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As Humans. Surely They Won't Ever Become So Stupid.

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

0BADC0DE
Member
From: Regnum Utriusque Siciliae
Registered: 2018-02-21
Posts: 312

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

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!


Maybe Computers Will Never Become As Intelligent
As Humans. Surely They Won't Ever Become So Stupid.

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