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?