Corrupted text at boot when graphics mode begin - how to fix?

[paju-21]

@paju-21

A bit more news to the problem.

I was in contact with AOC to get updated EDID but turned out to be waste of time. Yes, they sent me EDID but this was older than what I already had and contained exactly the same info. I found from elsewhere that there have been issues with YcBR mode and forcing EDID to RGB has solved some issues. I modified the EDID according to instructions but there’s a problem in loading it at boot phase. Everything should be OK but yet it fails to find the file (err -2).

Due to a need for 2nd UHD display I bought a new one and connected that instead. Still have an issue with 30Hz update rate but i need to tweak more.

Boot issue remains but now the monitor provided maybe crucial information. The resolution where the corruption exists is actually 1920x2160 - not 3840x2160. Dunno from where this comes from but clearly this is not valid resolution.

Correction: resolution is valid as such but according to xrandr --prop the update rate for 1920x2160 resolution should be 60 but it is 30. So this is mismatching at least.

Tried making 3840x2160@60 mode but that led to black screen. Pixel clock is higher than what DTD allows (594MHz vs 712MHz):

cvt 3840 2160 
# 3840x2160 59.98 Hz (CVT 8.29M9) hsync: 134.18 kHz; pclk: 712.75 MHz 
Modeline "3840x2160_60.00"  712.75  3840 4160 4576 5312  2160 2163 2168 2237 -hsync +vsync