I have a Medion notebook E4253 and a Dell monitor U2720Q. The notebook has a USB-C with DisplayPort port and I would like to use the Dell monitor with it. But unfortunately I get no signal when I connect the USB-C cable that comes with the monitor. The monitor also has an integrated HUB, which is recognized by the operating system without a problem as soon as I connect the notebook with the USB-C cable.
lsusb without connected USB-C cabel
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 8087:0aaa Intel Corp. Bluetooth 9460/9560 Jefferson Peak (JfP)
Bus 001 Device 003: ID 058f:3822 Alcor Micro Corp. USB 2.0 Camera
Bus 001 Device 002: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
lsusb with connected USB-C cabel
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 004: ID 8087:0aaa Intel Corp. Bluetooth 9460/9560 Jefferson Peak (JfP)
Bus 001 Device 003: ID 058f:3822 Alcor Micro Corp. USB 2.0 Camera
Bus 001 Device 002: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
Bus 001 Device 016: ID 0451:82ff Texas Instruments, Inc.
Bus 001 Device 015: ID 0451:8442 Texas Instruments, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
The window manager is wayland.
Currently, after much google, I unfortunately do not know what to do and I could not fix the problem. I would rule out a defect in the cable and monitor, since I still have a MacBook and here everything works plug & play.
If you have a type-C to display port adapter on hand to test with, it should help further to isolate if it is a hardware of software issue.
Sometimes system Firmware are controlling the functions of multi-function ports. Please do check the System Firmware settings and if firmware updates are available or not.
A little update on this issue:
I have now ordered a USB-C to DisplayPort cable. After trying it out, I have now unfortunately encountered another problem.
if I plug in the cable while the computer is running, both screens go black. If I unplug the cable again, then the screen of the notebook remains black and I have to restart the notebook via the power button to geht ist back working.
If the cable is plugged in during the boot process, everything works fine - only the integrated hub is not recognized. But, I don’t care about that for now.
One more thing: I read again in the specifications of the notebook. It says that a second display via the USB-C port only works with a corresponding USB-C to DisplayPort adapter. My original issue is a hardware problem and not a problem with Linux or Fedora!
Ok, it really seems to be a kernel problem. With the currently installed kernel 5.11.14-200.fc33.x86_64 hot plug does not work — only soft plug. If I change to kernel 5.8.15-301.fc33.x86_64 soft and hot plug is working
I faced similar issues as you and found this thread. I have a Dell DA310 USB-C Dock, on which the monitor wasn’t detected over Displayport, even on Windows.
For me the solution was to pull the power plug of the display, effectively rebooting it.
Perhaps worth a shot for you too. I have observed on several displays that the powersaving features over Displayport are unreliable (e.g. screen stays blank instead of going to standby), so this may very well help you too.