netdev - Re: [PATCH 2/3] dt-bindings: leds: Add `excludes` property

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Date:   Thu, 14 Oct 2021 12:43:09 +0200
From:   Marek Behún <kabel@...nel.org>
To:     Pavel Machek <pavel@....cz>
Cc:     devicetree@...r.kernel.org, linux-leds@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>, robh+dt@...nel.org,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: leds: Add `excludes` property

On Thu, 14 Oct 2021 12:29:18 +0200
Pavel Machek <pavel@....cz> wrote:

> Hi!
> 
> > Some RJ-45 connectors have LEDs wired in the following way:
> > 
> >          LED1
> >       +--|>|--+
> >       |       |
> >   A---+--|<|--+---B
> >          LED2
> > 
> > With + on A and - on B, LED1 is ON and LED2 is OFF. Inverting the
> > polarity turns LED1 OFF and LED2 ON.
> > 
> > So these LEDs exclude each other.
> > 
> > Add new `excludes` property to the LED binding. The property is a
> > phandle-array to all the other LEDs that are excluded by this LED.  
> 
> I don't think this belongs to the LED binding.
> 
> This is controller limitation, and the driver handling the controller
> needs to know about it... so it does not need to learn that from the
> LED binding.

It's not necessarily a controller limitation, rather a limitation of
the board (or ethernet connector, in the case of LEDs on an ethernet
connector).

But I guess we could instead document this property in the ethernet PHY
controller binding for a given PHY.

Marek