Regulator support for gpio-leds

[Snevzor]

Issue
I have some LEDs that are controlled using GPIOs connected to mosfet gates because the LEDs are connected to a dedicated fixed power regulator.
I can't seem to find a way to automatically turn on the regulator when using the LEDs in my application.

Describe the solution you'd like
It seems that "vin-supply" is what I need, but it appears not implemented for gpio-leds.
Actually in my case "supply-gpios" is probably better as the LEDs are the only consumers of the regulator.

Describe alternatives you've considered
The alternative is to control the enable pin of the regulator before using the LEDs (using an inferred binding in /zephyr,user perhaps), but as we have an application for two different HW setups (with only one setup using the regulator) this would require some ugly #ifdef constructions.
Are there other solutions already available?

[henrikbrixandersen]

You could represent the regulator as a regular and turn that on at boot time - that would allow the GPIO LEDs to be controlled as if the regulator is always-on?

[Snevzor]

My apologies. I forgot to underline that I need the regulator turned off when the LEDs are not used due to power restrictions.

[henrikbrixandersen]

My apologies. I forgot to underline that I need the regulator turned off when the LEDs are not used due to power restrictions.

I would likely write a custom LED driver for that, then. The driver could keep track of LEDs being on and turn off the regulator once the last LED is turned off. The LED driver itself could utilize the regulator API for controlling the regulator.

[Snevzor]

Thanks for the suggestion @henrikbrixandersen. Could you perhaps direct me to a sample where the regulator API is currently used? I'm trying to look for "vin-supply"/"vin_supply" without any result.

[henrikbrixandersen]

Thanks for the suggestion @henrikbrixandersen. Could you perhaps direct me to a sample where the regulator API is currently used? I'm trying to look for "vin-supply"/"vin_supply" without any result.

I don't think we have any in-tree users of https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/drivers/regulator.h except for the tests in https://github.com/zephyrproject-rtos/zephyr/tree/main/tests/drivers/regulator/fixed

[Snevzor]

Ok, I'll use the always on approach first to test my hardware prototypes and I will have to come back to this soon.
For me it would make sense to make the changes to the existing pwm-leds driver and perhaps try to get it upstream. Would that be a better idea compared to writing my own?

[xyzzy42]

It would be nice to clarify in the documentation that neither vin-supply nor supply-gpios do anything. They are present in the bindings for every I2C, I3C, SPI and regulator device, but no device uses them. Unlike Linux, where devices with supply bindings do actually enable their supplies.