Re: [PATCH v2] net: phy: Handle both led@0 and led subnode name for single-LED PHYs

[Marek Vasut <marex@denx.de>]

On 1/20/25 5:35 PM, Andrew Lunn wrote:
> On Mon, Jan 20, 2025 at 10:02:46AM +0100, Marek Vasut wrote:
>> 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.

>>   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 ?