Is it possible to apply a Device Tree overlay to U-boot's Device Tree via U-boot shell commands? [closed] - u-boot

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Say I would like to make changes to the following Device Tree node in this Device Tree for U-boot:
/* SDHCI is used to control the SDIO for wireless */
&sdhci {
#address-cells = <1>;
#size-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&emmc_gpio34>;
status = "okay";
bus-width = <4>;
non-removable;
mmc-pwrseq = <&wifi_pwrseq>;
brcmf: wifi#1 {
reg = <1>;
compatible = "brcm,bcm4329-fmac";
};
};
In my case, I would like to change the following line:
pinctrl-0 = <&emmc_gpio34>;
to
pinctrl-0 = <&sdhost_gpio48>;
Can I create a Device Tree overlay and apply this overlay via U-boot commands once U-boot is running?
My goal is that I want U-boot's device tree to be adjusted in the above manner when I run my standalone binary via U-boot's go command.
The overlay that I have created is here:
/dts-v1/;
/plugin/;
/ {
compatible = "raspberrypi,3-model-b-plus", "brcm,bcm2837";
model = "Raspberry Pi 3 Model B+";
fragment#0 {
target = <&sdhci>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&sdhost_gpio48>;
status = "okay";
bus-width = <4>;
non-removable;
mmc-pwrseq = <&wifi_pwrseq>;
brcmf: wifi#1 {
reg = <1>;
compatible = "brcm,bcm4329-fmac";
};
};
};
};
I've been broadly following U-boot's documentation here regarding loading and applying Device Tree overlays; however, I've noticed this documentation doesn't seem applicable to what I'm trying to achieve. Below are the steps I have taken so far:
I first create the fdtovaddr environment variable like so:
U-Boot> setenv fdtovaddr 0x1000000
Then I load my compiled overlay into fdtovaddr:
U-Boot> fatload mmc 0 ${fdtovaddr} sdhci_overlay.dtbo
Then I specify the base binary device tree as U-boot's Device Tree like so:
U-Boot> fdt addr ${fdt_addr}
Then I try to apply my overlay like so:
U-Boot> fdt apply ${fdtovaddr}
However, I get the following output:
failed on fdt_overlay_apply(): FDT_ERR_BADMAGIC
base fdt does did not have a /__symbols__ node
make sure you've compiled with -#
This makes sense because as per the docs, the base U-Boot Device Tree needs to be compiled with the -# command line switch and I'm assuming U-Boot's Device Tree was not:
It requires both the base device-tree and all the overlays to be compiled with the -# command line switch of the device-tree compiler so that symbol information is included.
The second part of the docs that made me realise the docs were not addressing my needs were the commands listed for booting the system as shown below:
Boot system like you would do with a traditional dtb.
For bootm:
=> bootm ${kerneladdr} - ${fdtaddr}
For bootz:
=> bootz ${kerneladdr} - ${fdtaddr}
The above commands are for passing the resultant overlayed Device Tree to a Linux Kernel Image via either the bootm or bootz shell command. This makes sense considering Linux uses a Device Tree to determine hardware availability etc and we are passing it a modified one via the above boot commands.
However, I would like to run a standalone via U-boot's go <address> command instead, which I believe doesn't accept an argument for a Device Tree (doesn't really make sense to either).
As such, is the conclusion that I've personally reached correct that it is not possible to manipulate U-boot's device tree while U-boot is running? Is the only option to manipulate U-boot's device tree manually and compile U-boot to generate a U-boot binary with my desired U-Boot Device Tree changes?
If not, please let me know how I can overlay U-boot's device tree during U-boot's runtime.