RK3399 | Additional device tree overlays

[mentorosso]

Hi,
I hope this is the right place to ask this: in latest dietpi version 9.14, i receive the following message while trying to install overlays "Overlays are not supported on based boards". I succeded with overlays installation with 9.11 release. Is there a download link of older releases for rock 4c+ ? 9.13 or 9.12 specifically. thx

[MichaIng]

Where do you see this message?

Device tree overlays are not exactly "installed", but part of the kernel package. On DietPi, they are enabled by defining them in /boot/dietpiEnv.txt. There is no part in our related code which would throw a message like "Overlays are not supported on based boards". If the defined overlay exists, it is tried to be applied, and either it succeeds, or you only see error messages when using a UART adapter and checking the bootloader output via serial console. There would then be a line saying:

Error applying DT overlays, restoring original DT

and above that hopefully some meaningful message how it failed.

Also in case tell me which overlay you tried to apply, among the ones shipped with the kernel package:

ls -l /boot/dtb/rockchip/overlay/

[mentorosso]

understand, thx for your reply. So the problem is in the overlay itself i think.
i was trying to install this custom overlay to enable usb OTG in peripheral mode https://github.com/herrfrei/dietpi-rpk4cp/blob/main/rk3399-dwc3-0-peripheral.dts

[MichaIng]

I would have it like this, but should work either way:

/dts-v1/;
/plugin/;
/ {
	compatible = "rockchip,rk3399";
	fragment@0 {
		target = <&usbdrd_dwc3_0>;
		__overlay__ {
			dr_mode = "peripheral";
		};
	};
};

What are the steps you do to compile and apply this overlay?

[mentorosso]

thanks!
i have solved installing an older dietpi image 9.8 that i found on my pc. it update itself to 9.14 but i could install the overlay without issue.
To answer your question, i rely on the script in the repo i linked to compile the overlay. Anyway, i'll keep your code for future reference.

[MichaIng]

I see. The script downloads a pre-compiled overlay. That will work only if the base device tree did not change too much. Likely Linux 6.12 broke it. A device tree should be recompiled for every new kernel.

Try this:

apt install device-tree-compiler
mkdir -p /boot/overlay-user
cat << '_EOF_' > /boot/overlay-user/rk3399-dwc3-0-peripheral.dtso
/dts-v1/;
/plugin/;
/ {
	compatible = "rockchip,rk3399";
	fragment@0 {
		target = <&usbdrd_dwc3_0>;
		__overlay__ {
			dr_mode = "peripheral";
		};
	};
};
_EOF_
dtc -I dts -O dtb -o /boot/overlay-user/rk3399-dwc3-0-peripheral.dt{b,s}o
G_CONFIG_INJECT 'user_overlays=' 'user_overlays=rk3399-dwc3-0-peripheral' /boot/dietpiEnv.txt

Generally, this overlay makes sense. By default that USB port is in host mode. There is an overlay which sets it to host mode, which is however redundant, as this is the case already. More sense makes this overlay which sets it to peripheral mode. If it works, I will add this to our kernel package.

[mentorosso]

it works! thank you very much! i think this will be very appreciated from other users.
I don't want to take advantage of you, but could you also try to make this other overlay works, the one that allows installing an RTC DS3231? https://github.com/herrfrei/dietpi-rpk4cp/blob/main/rk3399-i2c7-ds3231.dts
maybe i'm missing somenthing, i think the default overlay avaliable is for ds1307 rtc, cause mine doesn't work if i enable it only from dietpi-config

[MichaIng]

It should work the pretty same way:

apt install device-tree-compiler
mkdir -p /boot/overlay-user
cat << '_EOF_' > /boot/overlay-user/rk3399-i2c7-ds3231.dtso
/dts-v1/;
/plugin/;
/ {
	compatible = "rockchip,rk3399";
	fragment@0 {
		target = <&i2c7>;
		__overlay__ {
			#address-cells = <1>;
			#size-cells = <0>;
			rtc: rtc@68 {
				compatible = "maxim,ds3231";
				reg = <0x68>;
				status = "okay";
			};
		};
	};
};
_EOF_
dtc -I dts -O dtb -o /boot/overlay-user/rk3399-i2c7-ds3231.dt{b,s}o
G_CONFIG_INJECT 'user_overlays=' 'user_overlays=rk3399-i2c7-ds3231' /boot/dietpiEnv.txt

[mentorosso]

thanks :)