Radxa Zero 2 Pro using Waveshare 4 inch DSI LCD

Hello,

Thank you for the great effort of Armbian having community support of this board.

I have a Waveshare 4inch DSI LCD with touch that I want to use it with Radxa Zero 2 Pro. They have a device tree overlay provided for Raspberry Pi and drivers for different kernels for RPi

And I found a kernel patch that seem to enable DSI here.

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I am using the latest build of Armbian for radxa-zero2 and it's Linux radxa-zero2 6.6.53-current-meson64

When I

find /lib/modules/$(uname -r) -type f -name '*dsi*'

It shows

/lib/modules/6.6.53-current-meson64/kernel/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.ko
/lib/modules/6.6.53-current-meson64/kernel/drivers/gpu/drm/panel/panel-dsi-cm.ko
/lib/modules/6.6.53-current-meson64/kernel/drivers/gpu/drm/bridge/nwl-dsi.ko
/lib/modules/6.6.53-current-meson64/kernel/drivers/gpu/drm/bridge/cadence/cdns-dsi.ko
/lib/modules/6.6.53-current-meson64/kernel/drivers/gpu/drm/bridge/ti-sn65dsi83.ko
/lib/modules/6.6.53-current-meson64/kernel/drivers/mtd/nand/raw/nandsim.ko

When I

zcat /proc/config.gz | grep DSI

It shows

CONFIG_MTD_NAND_NANDSIM=m
CONFIG_DRM_MIPI_DSI=y
CONFIG_DRM_PANEL_DSI_CM=m
CONFIG_DRM_NWL_MIPI_DSI=m
# CONFIG_DRM_SAMSUNG_DSIM is not set
CONFIG_DRM_TI_SN65DSI83=m
# CONFIG_DRM_TI_SN65DSI86 is not set
CONFIG_DRM_CDNS_DSI=m
CONFIG_DRM_CDNS_DSI_J721E=y
CONFIG_DRM_DW_MIPI_DSI=y
CONFIG_DRM_MESON_DW_MIPI_DSI=y

Questions

AFAIK, that means the DSI interface is enabled and what I need to do is to compile a .dtbo device tree overlay based on Waveshare's and then load it into the system? 

And I assume the LCD needs some kind of 'driver' but Waveshare only provides some .ko and .dtso files in their GitHub repo. They have as recent as kernel 

6.6.20, can I use that driver and how?

As for compiling a device tree source DTS into a Device Tree Blog DTB, do I use the traditional way of 

dtc -I dts -O dtb -o output_file.dtb input_file.dts

or using

armbian-add-overlay

(however the documentation says DT overlays are a Work-in-Progress (WIP) feature, present only in certain images.)

Is there a way that I can verify if the DSI interface is functioning at all before I move on to the driver and overlay issue? That way I won't be working with too many uncertainties. I measured some of the pins on the DSI port on the monitor side and they seem to be 'functioning` (as there are pins with voltages and a 3.3v, plus there's  LED on the monitor that is blinking - I didn't go as far as checking if the 3.3v pin is in accordance of the Radxa Zero 2 Pro side for the DSI port, nor I did try to logic analyse other pins)

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I have tried to compile Armbian and choose ` > Device Drivers > Graphics support > DRM support for MIPI DBI compatible panels > *

Edited October 16, 20241 yr by Frankie Yuen