I recently installed the latest Armbian image into my Rock5B,
the neofetch output is here:
I used my portable 1080P monitor to finish the install process.
This 1080P monitor works correctly, but when I want to use my Lenovo X24q 2K monitor,
it cannot be recognized.
I don’t know how the mechanism works, but it seems that I can use force resolution to solve this.
Any idea about this?
Which display port do you connect the 5B to? HDMI or USB C?
THX for help
I use HDMI port0 to connect monitor
I followed the Rockchip debug manual
and use the command echo on > /sys/class/drm/card0-HDMI-A-1/status
to force open the HDMI port, but I got these message through dmesg
I changed another cable and have no issue with i2c error.
But this monitor still can’t be detected by rock board on startup.
If I use echo on > /sys/class/drm/card0-HDMI-A-1/status to force enable this monitor,
it will light up and get only 1920x1080 resolution.
I tried to use my Archlinux machine to decode edid information of this monitor and it looks like below
AFAIK You need a DT-overlay for 2K monitors to work.
I used this overlay yesterday via armbian-add-overlay command,
but still seems didn’t work.
And I contected the author of this overlay, got the idea that the newest kernel fixed this issue.
So I also rebuilt the kernel with armbian build tool.
But things still didn’t work 
The output of dmesg | grep hdmi is below:
[ 8858.335913] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8858.353924] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8868.856276] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8868.883683] rockchip-hdptx-phy-hdmi fed60000.hdmiphy: hdptx_ropll_cmn_config bus_width:16a8c8 rate:1485000
[ 8868.884071] rockchip-hdptx-phy-hdmi fed60000.hdmiphy: hdptx phy pll locked!
[ 8868.884248] dwhdmi-rockchip fde80000.hdmi: final tmdsclk = 148500000
[ 8868.888597] dwhdmi-rockchip fde80000.hdmi: don't use dsc mode
[ 8868.888615] dwhdmi-rockchip fde80000.hdmi: dw hdmi qp use tmds mode
[ 8868.888642] rockchip-hdptx-phy-hdmi fed60000.hdmiphy: bus_width:0x16a8c8,bit_rate:1485000
[ 8868.888903] rockchip-hdptx-phy-hdmi fed60000.hdmiphy: hdptx phy lane locked!
[ 8868.974189] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8878.012315] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8878.024266] dwhdmi-rockchip fde80000.hdmi: use tmds mode
[ 8878.108232] dwhdmi-rockchip fde80000.hdmi: use tmds mode
I changed my cable and got 2K resolution after force power up my monitor 
And the only problem left is the monitor can not light up when the board starts up.
In the other word: cannot detect 2K automatically