On 1/20/25 5:35 PM, Andrew Lunn wrote:

On Mon, Jan 20, 2025 at 10:02:46AM +0100, Marek Vasut wrote:

quoted

In case a PHY supports only one LED in total, like ADIN1300, and this LED
is described in DT, it is currently necessary to include unit address in
the LED node name and the address-cells have to be set to 1:

leds {
   #address-cells = <1>;
   ...
   led@0 {
     reg = <0>;
     ...
   };
};

For a single LED PHY, this should not be necessary and plain 'led' node
without unit should be acceptable as well:

leds {
   ...
   led {
     ...
   };
};

So how do other subsystems handle this? SPI with only a single chip
select line?

I believe for SPI, it is always mandatory to have 'reg' property.

Standalone LED controllers with a single LED?

The GPIO LEDs driver does not enumerate the LEDs at all, so there is no 
'reg' property needed in any case, but I don't think this is really 
applicable for the PHY LEDs, which depend on the ordering within each PHY.

A PWM with a single output?

Reference the controller node itself, similar to how single output clock 
controller works.

quoted

  drivers/net/phy/phy_device.c | 15 +++++++++++++--

What about the device tree binding? Does it already have the reg
property as optional?

Documentation/devicetree/bindings/net/ethernet-phy.yaml does not, but 
that can be changed if desirable . If not desirable, then I can just 
discard this patch ?