Dts aliases label bug?

[professor_jonny]

I'm having issues compiling a dts depending on the label format and I don't know if I am interpreting things wrong and the node label and led label property are different things.

It says in the linux documentation under leds:

label:
description:
The label for this LED. If omitted, the label is taken from the node name
(excluding the unit address). It has to uniquely identify a device, i.e.
no other LED class device can be assigned the same label. This property is
deprecated - use 'function' and 'color' properties instead.
function-enumerator has no effect when this property is present.

https://www.kernel.org/doc/Documentation/devicetree/bindings/leds/common.yaml

if I define it as below it compiles:

aliases {
led-boot = &led_system_red;
};

led_system_red: system-red {
gpios = <&tlmm 25 GPIO_ACTIVE_HIGH>;
color = <LED_COLOR_ID_RED>;
};

If I format it like this, it fails to build:

aliases {
led-boot = &led_system_red;
};

system-red {
label = led_system_red
gpios = <&tlmm 25 GPIO_ACTIVE_HIGH>;
color = <LED_COLOR_ID_RED>;
};

This is my build error:

ERROR (path_references): /aliases: Reference to non-existent node or label "led_system_red"

I guess using the node name for the aliases fixes my issue but is this a bug or not?

[pwned]

I don't really have a clue about DTS. But I think you've just missed the semicolon after label. So it has to look like:

label = "led_system_red";

[Hostle]

@pwned

I don't really have a clue about DTS. But I think you've just missed the semicolon after label. So it has to look like:

label = "led_system_red";

yep thats likely the issue

[professor_jonny]

sorry that is just my typing error when pasting into the forum the semi colon was present when building the DTS.

I think the led label and node label are formally different properties.

[pwned]

Sorry it's a while ago I've messed around with DTS.

aliases {
      led-boot = &led_system_red;
};

Then you access to it with &.

So it has to look like:

&led_system_red {
      label = "system-red";
      gpios = <&tlmm 25 GPIO_ACTIVE_HIGH>;
      color = <LED_COLOR_ID_RED>;
};

You could also put it into a node like:

leds {
	compatible = "gpio-leds";
	led_system_red: system-red {
	label = "system-red";
	<&tlmm 25 GPIO_ACTIVE_HIGH>;
	};

But don't nail me on that. I don't have a clue if this node approach is outdated already or not. There are others with more clue then me for sure.

[professor_jonny]

The bottom suggestion does not work it is the same format as my code,

I think the & is used as to reference to a node it is often used to point to an include to reference a section in a .dtsi file for example i is why it is used on the alias to reference the node.

I found from my playing around that an alias only likes the format below using the label as a reference I could not get it to notice the node::

[label:] node-name[@unit-address] {
[properties definitions]
[child nodes]
};

[Hostle]

aliases {
		serial0 = &blsp1_uart1;
		...

		led-boot = &led_system_blue;
		led-failsafe = &led_status_white;
		led-running = &led_status_white;
		led-upgrade = &led_system_blue;
	};

leds {
		compatible = "gpio-leds";
		pinctrl-0 = <&leds_pins>;
		pinctrl-names = "default";

		led_system_blue: led_system_blue {
			label = "led_system_blue";
			gpio = <&tlmm 24 0>;
			default-state = "on";
		};
		
		led_status_white: led_status_white {
			label = "led_status_white";
			gpio = <&tlmm 23 0>;
			default-state = "off";
		};
	};

&tlmm {
...
leds_pins: leds_pins {
		led_system_blue {
			pins = "gpio24";
			function = "gpio";
			drive-strength = <8>;
			bias-pull-down;
		};
		
		led_status_white {
			pins = "gpio23";
			function = "gpio";
			drive-strength = <8>;
			bias-pull-down;
		};
	};

all relevant led nodes and phandles from a working dts, in which the leds function properly

[professor_jonny]

@professor_jonny

This property is
deprecated - use 'function' and 'color' properties instead.

I don't know if they refer to the label property of the node or the label within the node property's

But that's what I have that compiles and works but it says in the Linux docs it says it is depreciated; I tried the other way and it does not work I'm just a little confused they have called two things label.

I think they mean the property label= is depreciated and instead use function and color to describe the led.

I think they mean this is a bad

		led_status_white: led_status_white {
			label = "led_status_white";

And this is good:

		led_system_red: red {
			color = <LED_COLOR_ID_RED>;
			function = LED_FUNCTION_STATUS;

It seems the aliases does not follow the label = and from my testing it does not follow the node either but I'm not sure I'm interpreting things correct.

[Hostle]

All I can say is, I am using this style in my dts and everything compiles and works perfectly building against against kernel 5.10 -> 6.6.56

[pwned]

I agree with @Hostle.

If I look into the document you've linked. I would say that the pointer "label" is deprecated? So why you want to use it then?

label:
description:
The label for this LED. If omitted, the label is taken from the node name
(excluding the unit address). It has to uniquely identify a device, i.e.
no other LED class device can be assigned the same label. This property
is deprecated - use 'function' and 'color' properties instead.
function-enumerator has no effect when this property is present.

Another example (without any use of "label"):

	aliases {
		led-boot = &pwr;
		led-failsafe = &pwr;
	};
...
	leds {
		compatible = "gpio-leds";

		pwr: pwr {
			color = <LED_COLOR_ID_ORANGE>;
			function = LED_FUNCTION_POWER;
			gpios = <&tlmm 28 GPIO_ACTIVE_HIGH>;
		};

		lan  {
			color = <LED_COLOR_ID_BLUE>;
			function = LED_FUNCTION_LAN;
			gpios = <&tlmm 29 GPIO_ACTIVE_HIGH>;
		};

		wlan2g  {
			color = <LED_COLOR_ID_BLUE>;
			function = LED_FUNCTION_WLAN;
			function-enumerator = <0>;
			gpios = <&tlmm 30 GPIO_ACTIVE_HIGH>;
			linux,default-trigger = "phy0radio";
		};

		wlan5g  {
			color = <LED_COLOR_ID_BLUE>;
			function = LED_FUNCTION_WLAN;
			function-enumerator = <1>;
			gpios = <&tlmm 31 GPIO_ACTIVE_HIGH>;
			linux,default-trigger = "phy1radio";
		};
	};
};

@professor_jonny

I think the & is used as to reference to a node

Y, and the error message you've posted is refering to a missing node or label. So either both is wrong or one of them is wrong. You said that label was a copy paste error. So the node is left.

[diederik]

When you use &<name-or-label> then that name or label needs to be defined elsewhere as it's (indeed) a reference.

So in the first example you have a label led_system_red so you can reference it.
In the second example you reference a label which doesn't exist, so it fails.

note that there is no point in having a label with the same value as the name. A label is specifically so you can use a different value then the name, usually something simpler.

[professor_jonny]

yip it is just there is two labels a node label and a label property the alias only works with a node label or a node name, documentation is not the best, I have it working now adn have dropped the label property in favour of function and colour and it works as intended.