I have a Measy (R-BOX) U4C rk3188. Before I recycled it I thought I would try to get a linux kernel running on it and found this these posts. I experimented with Armbian_21.02.0-trunk_Rk3188_focal_current_5.10.6_xfce_desktop.img from 13JAN. (Thanks Balbes!)

It boots with rk3188-rbox-cs968.dtb and most everything works but the video ouput is color shifted. So HDMI video output is fine but the colors wrong and HDMI audio is not working.  

I took apart the Android firmware that was on the thing but with a V3 kernel without uboot it is kind of difficult to see into the kernel. I assume the device tree is somehow off for this system or, more likely the uInitrd is loading an incorrect fb module. 
    

Console: switching to colour frame buffer device 240x67 
rockchip-drm display-subsystem: [drm] fb0: rockchipdrmfb frame buffer device  

    
Other errors are:

    Broadcom
    brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43362-sdio.rockchip,rk3188.txt failed with error -2
    brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43362-sdio for chip BCM43362/1
    brcmfmac: brcmf_c_process_clm_blob: no clm_blob available (err=-2), device may have limited channels available
    brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM43362/1 wl0: Apr 22 2013 14:50:00 version 5.90.195.89.6 FWID 01-b30a427d
    Bluetooth: hci0: command 0x0c03 tx timeout
    Bluetooth: hci0: BCM: Reset failed (-110)    
    ieee80211 phy0: brcmf_cfg80211_add_iface: add iface p2p-dev-wlan0 type 10 failed: err=-5
    brcmfmac: brcmf_sdio_dpc: failed backplane access over SDIO, halting operation    
    brcmfmac: brcmf_sdio_bus_rxctl: resumed on timeout
    ieee80211 phy0: brcmf_run_escan: error (-110)    
    
    HDMI audio
    hdmi-audio-codec hdmi-audio-codec.0.auto: ASoC: error at snd_soc_dai_hw_params on i2s-hifi: -22
    it66121 2-004c: it66121_audio_hw_params: sink has no audio

 

However the Broadcom WIFI is working and Bluetooth appears to be working as well although I did not try to pair any device.

I have a tarball of all the logs if that would help but since there is no error other than a beautiful green/cyan. I don't know how to proceed to compile a new kernel/modules for this.

 

Any direction getting the correct device tree/kernel/modules built for this?

Moved your post to the Rockchip CPU Box forum.  I do not work with rockchip based boxes myself, but there are a few people who do in this forum that may be able to provide you some guidance.  The RK3188 is an older 32bit cpu.  A lot of the effort recently around here is support for more recent 64 bit based cpus.

This post was originally posted to the mega thread: https://forum.armbian.com/topic/14232-single-armbian-image-for-rk-aml-aw-armhf-armv7

Well I am getting closer. I just need to make the dts bind vop correctly or recompile the fb.ko when I figure it out. There doesnt seem to be a way to pass parameters at boot. I have decompiled an android zImage so I will spend some time with that...