Debugging modesetting problem

[Jona Stubbe]

Hi AMD graphics developers,

I've recently hit a modesetting problem: when I used the DisplayPort KVM 
switch that I got yesterday to connect my PC (running Arch Linux) to my 4K 
monitor, it only worked in 3 out of about 60 times of switching/replugging the 
cable (the BIOS always manages to put something onscreen, though).
I've tried both graphics cards available to me right now: a Polaris (RX 480) 
and a Cayman (HD 6950/6970) and neither of them modesets properly and 
reliably.
I wouldn't be opposed to doing some work to fix this myself, as this is a good 
opportunity for me to get into system development, however I don't know where 
to start.
I have full (root if required) access to the system, so building/running 
custom kernels or whatever is necessary is not a big problem. However, logic 
analysers (or whatever you may need to find out what actually goes over the 
wire) are out of my reach. Is this something I can tackle?

Yours faithfully
Jona Stubbe

PS: if there is a shorter-latency way of asking this kind of question (like an 
IRC channel), I'd be interested too :)
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