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Setup
Monitor: LG 32GK850G-B
Graphics Card: AMD RX5700XT connected via DisplayPort
KVM Switch: 2560 x 1440 @ 60 Hz via DisplayPort
Kernel: 5.16.4-arch1-1
DE: XFCE
Background
My main monitor is connected to my graphics card via a KVM switch, with DisplayPort input and output set as 2560 x 1440 @ 60 Hz. I have a secondary monitor (old TV) connected via a HDMI, which can support 1920x1080.
When the main monitor is connected directly to the graphics card there are no problems with the display. However, when the signal goes through the KVM, it only achieves 2560 x 1440 @ 60 Hz after flicking between sources a few times on the KVM, otherwise the display switched to a maximum resolution of 1024x768.
To remedy this, I set a custom EDID* as part of the early KMS, which ensured that the display booted at 2560 x 1440 @ 60 Hz. Unfortunately, now whenever I switch the monitor off or change sources on the KVM-switch, the display is compressed along the x-axis to a quarter of its size. The only resolutions it will support correctly (without a reboot) are 1024x768 and below.
*The EDID file was extracted from when the graphics card was connected directly to the monitor without the KVM-switch
I have tried setting the resolution via xrandr, using different cables, changing xorg.conf settings, installing and removing amdgpu pro packages.
I have read around this topic to the best of my ability but I am stuck and unable to proceed further.
If anyone could provide any advice, it would be most welcome.
Logs
Note: in the dmesg, the error "[drm] *ERROR* AMDGPU DM aux hw bus 2: DPCD failed read at register 0x201" occurs when switch the display to my other computer
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