Re: [PATCH net-next 2/8] dt-bindings: net: lan9645x: add LAN9645X switch bindings

[Conor Dooley <conor@kernel.org>]

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On Fri, Mar 06, 2026 at 04:08:01PM +0100, Jens Emil Schulz Ostergaard wrote:
> On Thu, 2026-03-05 at 18:31 +0000, Conor Dooley wrote:
> > On Thu, Mar 05, 2026 at 01:57:37PM +0100, Jens Emil Schulz Ostergaard wrote:
> > > On Tue, 2026-03-03 at 19:04 +0000, Conor Dooley wrote:
> > > > On Tue, Mar 03, 2026 at 03:18:45PM +0100, Andrew Lunn wrote:
> > > > > > +        properties:
> > > > > > +          microchip,led-drive-mode:
> > > > > > +            $ref: /schemas/types.yaml#/definitions/uint32
> > > > > > +            description: |
> > > > > > +              Set the LED drive mode for the copper PHY associated with
> > > > > > +              this port.
> > > > > > +
> > > > > > +                0 - LED1 and LED2 in open-drain mode
> > > > > > +                1 - LED1 in active drive mode (can be used for single-LED
> > > > > > +                    configurations requiring active drive)
> > > > > > +                2 - Reserved
> > > > > > +                3 - LED1 and LED2 in active drive mode
> > > > > > +            minimum: 0
> > > > > > +            maximum: 3
> > > > > 
> > > > > I doubt the DT Maintainers will accept that. This looks a lot like a
> > > > > value you write into a register. How are active drive and open-drain
> > > > > described in other DT bindings? Is there something you can reuse?
> > > > 
> > > > I had a quick look and I didn't see anything really that stood out to me
> > > > that would be a drop-in replacement.
> > > > I also tried looking in the datasheet for more information on these
> > > > modes, but I couldn't see anything obvious. For example, there were zero
> > > > hits for "drain" in either LAN9645xS or LAN9645xF datasheets.
> > > > 
> > > > That said, yea you're right about DT maintainer feelings about it.
> > > > There's a couple things I could suggest, but I'd like to know about what
> > > > mode 1 means for LED2 first. If there's actually nothing similar, what
> > > > about representing each led with a child node and having open-drain be
> > > > the default with a property in the child for active-drive?
> > > > 
> > > > > 
> > > > > For 1, what happens to LED2? Not used at all?
> > > 
> > > In mode 1 LED2 will be open-drain. This mode only makes sense if you have
> > > just 1 LED. With two LEDs mode 0 or mode 3 should be used.
> > 
> > Could we then have child nodes for each led, and have a property in each
> > that sets the mode to either open-drain or active-drive? Or am I just
> > inserting complexity by asking for that?
> 
> I think it sounds sensible, I will add this.


You don't need a property for each, just make one mode the default (prob
open-drain given it's the 0 setting, but whatever is default out of
reset for the part) and have the property for the other mode. Just
some bool property like "microchip,active-drive" or whatever.

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