Hey,

I'm facing some problems with connecting my Laptop (Thinkpad T470s) to my TV over HDMI. Some info about my System:

Operating System: KDE neon 5.23
KDE Plasma Version: 5.23.5
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.3
Kernel Version: 5.13.0-27-generic (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-7300U CPU @ 2.60GHz
Memory: 15.4 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 620

The TV is detected and can be configured in the display settings, but if I set the resolution to 1920x1080 there is no video on the TV. With 1600x900 the video is displayed but with some artifacts. 1280x720 works well.
The xrandr output for HDMI-2 is:

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HDMI-2 connected 1280x720+1920+0 (normal left inverted right x axis y axis) 1060mm x 626mm
   1920x1080     60.00 +  50.00    59.94    30.00    25.00    24.00    29.97    23.98 
   1920x1080i    60.00    50.00    59.94 
   1680x1050     59.88 
   1600x900      60.00 
   1280x1024     75.02    60.02 
   1440x900      59.90 
   1366x768      59.79 
   1280x800      59.91 
   1152x864      75.00 
   1280x720      60.00*   50.00    59.94 
   1024x768      75.03    70.07    60.00 
   832x624       74.55 
   800x600       72.19    75.00    60.32 
   720x576       50.00 
   720x576i      50.00 
   720x480       60.00    59.94 
   720x480i      60.00    59.94 
   640x480       75.00    72.81    66.67    60.00    59.94 
   720x400       70.08 
   1920x1080_60.00  59.96 


You can see in the last line that I already tried setting a custom mode. The TV displays the video then, but with artifacts and its also breaking up occasionally.

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$ cvt 1920 1080 60
# 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
$ xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
$ xrandr --addmode HDMI-2 1920x1080_60.00
$ xrandr --output HDMI-2 --mode 1920x1080_60.00


I know that the TV+Cable is OK, because I've been using the setup with my T430 + KDE Neon in Full HD before.
Seems like this is a known problem on various software/hardware setups, but anyway I could not find a solution that worked for me... I hope someone can help!

Regards,
Tim